Black Friday 2020 — rays of hope for a better future

Some old tricks and deceptive practices, but two e-shops have seen the light and are being honest with their customers — with our help.


You can read the original Czech version of this article here.

TLDR: The number of products on offer and the size of real discounts at Czech e-commerce retailers this year was much the same as last Black Friday. The discounts covered about 1–2% of all stock, or about 10,000 products. The stores advertised discounts of “up to 80%” and displayed discounts of around 30% on most products. On average, the real discounts were only 10–20%.

The good news is that two e-commerce retailers, and, tried hard to calculate their discounts correctly before Black Friday. Others were still using retail prices, even though they practically never sell the items at those prices. The new EU directive on consumer protection, which should be transposed into Czech law next year, should prevent them from doing this.

In the e-commerce retailers that we have been monitoring for some time, we found only a few potentially deceptive practices — and in most cases we believe these to have been errors in pricing. Unfortunately, this isn’t true of some newer additions. This year’s biggest disappointment was, which discounted half of its stock for Black Friday and displayed an average discount of 44%. In reality, the product prices were reduced by only 1%.

Outside of Black Friday, we discovered some other tricks that e-commerce retailers use to manipulate their customers, such as different prices when coming from product comparison sites than on the website (, higher original prices so that the product isn’t really discounted (, or products on sale practically all the year round ( We also registered problems with the partner programs of and

Lots of improvements have also been made to Hlídač Shopů (“Shop Watcher”), which is under continuous development in cooperation between Apify, TopMonks and Keboola. We’ve released a new Safari extension, added seven new Czech and nine new Slovak e-commerce retailers, switched to new EU methodology for calculating real discounts, modified and unified the appearance of all web extensions for different browsers, and launched the first beta version of our top discount dashboard.

Black Friday sale advertisement
Photo by Tamanna Rumee on Unsplash

Overview: Black Friday 2020

The table below is an overview of all the e-commerce retailers we monitor that participated in the Black Friday event. Some launched it at the end of October, others joined during the last week of November. None of the online stores we monitor only had Black Friday on “Black Friday”, as is the case in much of the rest of the world (with Cyber Monday on top). For example, had some advance “Black Friday tastings”, although these, in their own words, shot them in the foot, as these tastings reduced the real discount on Black Friday (see discussion below).

The table shows you the total number of products on offer in each store, the number of products included in the Black Friday promotion (this is for the whole duration, as the products offered changed slightly every day), the average listed discount, the real discount as calculated by us, and the start date of the promotion.

a table with a list of e-shops comparing the Black Friday discount with the actual discount
Overview of Black Friday 2020

As you can see from the overview, only a few products typically get included in Black Friday. The only exception was, which included about half of its permanent stock in its Black Friday event. However, there were few real discounts to speak of in this case. The huge range of products at is mainly due to partner sales and product variants, especially in the fashion department. By the way, and already provide us with the prices of all their stock on a daily basis, so we don’t have to monitor them ourselves. We hope that more online retailers will decide to do this in future.

During Black Friday last year, even the big e-commerce retailers complained to us that they couldn’t be the only stores not to offer discounts of up to 80%. They claimed that Czechs were so ravenously hungry for discounts that they would punish any store brave enough to show the real reference (crossed-out) price for a product before it was discounted.

This status quo can be illustrated by this statement [translated from Czech — see this article in Czech for the original statement] from the press spokesperson of and we received similar comments from the other e-commerce retailers mentioned above:

We calculate all discounts on MALL.CZ from recommended retail prices. The recommended retail price, the one stated before the discount, is always that proposed by the manufacturer or distributor when launching each new product. Other traders on the market also work according to this methodology, and the amount of the discount is then more easily comparable.

As explained above, and as can be seen from data collected using web scraping over almost the last three years, e-commerce retailers do not sell these products at their retail prices before Black Friday. In fact, they mostly do not even sell them at these prices when they are first made available. That means that the eye-catching discount of “up to 80%” that is calculated from the retail price is actually much lower when the discount is calculated from the actual price before the event — often coming out at an average of 20%.

So we’re very pleased to see that two e-commerce retailers have, with our help, started to display real crossed-out prices, and therefore real discounts, at least for the products listed in the Black Friday event. listed real discounts calculated from the lowest price at which the products were sold in October. They even asked for our assistance in auditing their calculations and corrected some of their discounts accordingly. For example, we discovered that some products had not been discounted at all during Black Friday, even though discounts had been advertised during the “tasting” events in October. We hope that a side effect of this cooperation is that there will be a return to a more reasonable approach to Black Friday in future — and to other discount events that online stores abuse throughout the rest of the year.

Let’s celebrate Alza’s new attitude with a real example:

screenshot of a sale price tag (from 12,999 CZK to 11,999 CZK) on with the Hlídačshopů graph
Real discounts at

This coffee machine from normally sells for CZK 13,000, although the price has been reduced to below CZK 12,000 several times this year. During last year’s Black Friday event, the product was on sale for effectively the same amount as this year, but the discount was calculated based CZK 21,000, a price at which it was last sold in the summer of 2018. This year, Alza finally used a reference price of CZK 13,000 (the lowest price in October) and displayed a real discount of 8%. This is identical to the real discount that we came up with. was brave enough to take a similar step. In their case, discounts for this year’s Black Friday were calculated according to the “last price before Black Friday”. Although this calculation does not cover cases where the sale price increases just before the event, it is still a great step ahead and away from the approach of calculating discounts based on recommended retail prices.

screenshot of a FAQ popup regarding discounts on
Real discounts on

We are very pleased with how both e-commerce retailers have taken the initiative and we hope that real discounts will start showing up even when there are no big promotional events. We especially hope that other online retailers will be inspired to follow the examples of and They should be encouraged to do so by the EU Consumer Protection Directive, which Member States should incorporate into law next year and apply by May 28, 2022, at the latest. For our purposes, the key section is in the amendments to Directive 98/6/EC:

1. Any announcement of a price reduction shall indicate the prior price applied by the trader for a determined period of time prior to the application of the price reduction.
2. The prior price means the lowest price applied by the trader during a period of time not shorter than 30 days prior to the application of the price reduction.

In order to prepare Czech e-commerce retailers for these rules, we have already implemented them into our methodology for calculating the real discount for Black Friday this year. More information on our methodology can be found on the Hlídač Shopů website (in Czech language only). Even and still don’t exactly apply this relatively strict interpretation, so in some cases their discounts are different from those we calculated.

Familiar old tricks

Let’s take a look at some examples of artificially increased discounts during Black Friday. We’ll focus on the online stores that we only started monitoring more recently. One of these is, which paradoxically requested themselves that we start monitoring them. included a total of 8,135 products in their Black Friday promotion, or almost half of their entire range of products. Unfortunately, we found an increase in the reference (crossed-out) price for 770 of them just before Black Friday. For example:

screenshot of a chest of drawers on sale at from 93,800 CZK to 36,499 CZK
Inflating the crossed-out price on

This chest of drawers has been sold on since August for the same CZK 36,499. Until October 16, when it was advertised at a 46% discount and the crossed-out price was shown as CZK 67,999. During October, this crossed-out price increased three times in total, and thus the advertised discount was gradually increased to 51%, 59%, and finally 61%. Subsequently, the product was included in the Black Friday, without a change in the price, at a beautiful 61% discount. has not yet responded to us, but after we shared this example on Twitter and after a piece on Czech television, they at least returned the crossed-out price and thus the advertised discount to the level before the artificial increase:

screenshot of a chest of drawers on sale at from 67,999 CZK to 36,499 CZK
And the return of the old price on

Another unbelievable example is this sexy mouse pad:

screenshot of a mouse pad on sale at from 499 CZK to 419 CZK
509% Black Friday increase on

On sale from July for CZK 69, but for CZK 419 in Black Friday. And after an additional 16% discount. Maybe those 28 customers who were just tracking it (check the bottom-left corner of the screenshot) just never took the bait.

At, we came across this Grundig thermometer:

screenshot of a thermometer on sale at from 1499 CZK to 999 CZK
Inflated crossed-out price on

On October 17, the price increased from CZK 999 to CZK 1,199, but at the same time the reference (crossed-out) price increased from CZK 1,099 to 1,499. Subsequently, the product was again discounted to CZK 999 for Black Friday, but the crossed-out price was increased to CZK 1,499. This created a 33% discount. If a discount of 17% from the price at which the product was sold before the event had been displayed, it would have been relatively fine (although rather unethical), but a discount of 33% from the inflated crossed-out price is already, in our opinion, explicitly misleading.

We received this response [translated from Czech — see this article in Czech for the original statement] to our request for a comment:

We set the discount from the price set by the supplier when the product is put on sale. In this particular case, however, there was an error in setting the price when browsing the product, and we subsequently corrected the price.

After another question as to whether it was acceptable to continue to offer such a product in the Black Friday sale, we were told:

The thermometer was included in the marketing event at a reduced price.

We also found similar examples on, which included just over 150 products in Black Friday. For example, this collagen duo pack:

screenshot of collagen on sale at from 1558 CZK to 719 CZK
Inflated crossed-out price on

The product was included in the Black Friday promotion. During the event, increased the price from CZK 399 to CZK 719. At the same time, the crossed-out price was increased from CZK 799 to CZK 1,558. We were disappointed that, after we published this example on Twitter, responded by dismissing our charts and claiming that they had never sold this product for CZK 399. However, the proof can be seen in the development of the average price of the product on, which has only one seller offering this product, namely

graph showing a rising tendency of the average product price
And the same product on

We understand that may have made an error when listing the product, but we would have hoped for a different reaction. On the other hand, the result of this Twitter poll carried out by the founder of may mean that there is a glimmer of light at the end of the tunnel:

screenshot of a Twitter poll on what users understand by a crossed-out price in e-shops (the "seller's last price" wins)
Pilulka founder polls users on Twitter about discounts

Another trick to conjure up an attractive discount is to increase the sale price just before the event, even just for a few days. This intelligent blind control on is a good example:

screenshot of a switch on sale at from 7110 CZK to 1671 CZK
Increased price just before Black Friday on

The product was sold at the crossed-out price of CZK 7,110 (actually only CZK 7,103) only on October 24 and 25 before Black Friday. During the promotion, it was then reduced by 76% to CZK 2,000, the price at which it was sold throughout practically all of 2020. entered Black Friday with a 25% discount on selected products. Among these, we found, for example, this hand cleansing gel:

screenshot of a cleansing gel at for the price of CZK 407
Black Friday price increases on

The Black Friday discount was a nice 25%, but this was nevertheless on a product that had increased in price by 216% that day. In addition, the 50ml variant was almost twice as expensive as the 200ml one on the same day.

Beyond Black Friday: everyday tricks

On, it’s a good idea to pay attention to something else — if you shop directly on the website, you get a more expensive price than if you come from a comparison website, such as

When shopping on the website, you receive a price of CZK 3,340:

screenshot of a perfume at for the price of CZK 3,340
You can get shown a more expensive price when shopping directly on

When you search for the same product on and click on the website, you get a cheaper price of CZK 3,069:

screenshot of a perfume at for the price of CZK 3,069
Compared to a cheaper price when you arrive from

Mountfield has an interesting attitude towards discounts. It offers practically all its products at discounts exceeding 50% all year round, and only a few times a year offers them without these discounts. For example, this infrared sauna was priced at between CZK 15,990 and CZK 17,490 from January 1 to October 18. The crossed-out price was CZK 36,790 for the entire period. The discount was therefore 55%. On October, the price increases 144% to the current price of CZK 41,490, a price which lasted until the time of writing (November 29):

screenshot of an infrared sauna on website for the price of CZK 41,490
Year-round sale on — almost

Mountfield’s statement [translated from Czech — see this article in Czech for the original statement] is as follows:

For us, it is certainly not an increase, but a return to normal sales prices, and of course we cannot rule out that sometime during the next year, we will reduce the price of selected commodities to customers in some promotions.
This year, however, it was a very unusual year due to Covid, so we had bigger or smaller discounts for a substantial part of the year, with the exception of the pre-Christmas season. also takes an interesting approach to discounts. Rohlik correctly calculates the discount from the price before the event, when the product is on sale, but when it is not on sale, it uses the retail price to calculate the discount. Paradoxically, it offers a bigger discount when the product is not on sale. These dishwasher tablets are a good example:

screenshot of dishwasher tablets on sale at from CZK 499 to CZK 299
Discount cycles on

By default, sells them for CZK 299.90 and regularly puts them on sale at CZK 249.90. If they are in a promotion, they have the correct crossed-out price of CZK 299.90 (17% discount), but if they’re not on sale, the crossed-out price is listed as CZK 499.90 (40% discount) with the label “permanently discounted price”. The exchange below shows that does not see anything strange about this:

a screenshot of a conversation on Twitter, where confirms to Hlídač Shopů that when a product is on sale, it gets a discount of 17% and when it is not, then 40%
Rohlik responds to us on Twitter

Partner sales on and

As part of our analysis, we also looked at partner sales from the largest online stores we monitor. Each of them presents these a little differently, but technically the way they work is the same. In both cases, the seller is a large e-commerce retailers ( or that buys the goods from the partner (and keeps a margin). The goods are then delivered to you by the partner. is building an “open internet marketplace” and its partner sales are duly marked as such:

screenshot of a product on sale at from CZK 3,110 to CZK 1,238 marked as a partner sale
Partner sales on

As last year, we found partner sales on where the crossed-out price was inflated before or during Black Friday. There was a total of 130 cases this year, which is an improvement compared to last year, when there were thousands. again reacted promptly and promised to fix the problem.

We are now in contact with the partner e-shops affected this time and we are working on an accelerated remedy. If this should happen again in the future, we will remove their offer from the website and end our cooperation.

Alza marks main partner sales as a “dropshipment”, but the product listings are not indicated in any particular way (Alza also recently launched another Alza Partner program, through which partners can offer vouchers for their services and goods). Unfortunately, the customer has no idea that these products are being offered by partners and will generally find out at the moment when splits the order into several shipments, with some of them coming from an “external warehouse”. The customer can also be surprised by a charge for two deliveries, as in the case below (Alza often consolidates shipments):

screenshot of a shopping cart on, with products divided into two orders
One order divided into two shipments on

Hlídač Shopů news

We’ve improved Hlídač Shopů for you in lots of ways since last Black Friday.

Newly monitored e-commerce retailers

This year we added a total of 7 Czech and 9 Slovak e-shops (the usual term for an e-commerce retailers in CZ and SK). The complete current list looks like this:,,,,,,,,,,,, Kosik. cz,,,,,,,,,,,,,,,,

New methodology for calculating real discounts

As already mentioned, we are preparing for the new EU rules. A description of our methodology can be found here (in Czech language only). After this year’s Black Friday, we plan to revise this. We are mainly waiting to see how it will be incorporated into Czech law.

Standardize appearance of web extensions and appearance

We’ve unified the technology used for displaying real discounts and price developments (using PWA). We are currently tuning the infobox with the real discounts and we are planning to simplify the display so that it doesn’t use a chart. We welcome your feedback on this issue on GitHub.

Sharing a real product discount

After verifying the real discount on the Hlídač Shopů website, you now have the option of sharing the result on Facebook or Twitter. It will look like this:

screenshot of Apple Airpods at with a 7% discount
Sharing real discounts with your friends

Safari extension

We’ve finally managed to release an extension for Safari. We even got to second place in the Free Utilities category this year!

screenshot of Safari extensions category in the App Store
Hlídač Shopů on the App Store

Top discounts

Hot from our “beta lab”, we bring you an overview of the biggest up-to-date real discounts from all the online stores monitored on the Hlídač Shopů website. This currently updates with a delay of one day:

screenshot of the Top discounts page at
Overview of Hlídač Shopů top discounts

So next time you can catch something like this:

screenshot of Airpods Pro on sale at from 7,290 CZK to 5,790 CZK
Amazing offer on

The Hlídač Shopů team

This non-profit project is still brought to you by enthusiasts from these Czech “startups”:

Apify is in charge of product monitoring and data analysis. The most work here is done by Zuzka.

TopMonks brings new functionalities to the website and debugs browser extensions. The main “hacking monkey” is Aleš.

Keboola provides its powerful data tool and Petr parachutes in with his SQL magic (currently needed for calculations according to the new methodology).

Fenek takes care of our PR, especially during Black Friday.

You can contact us at Or find discounts and non-discounts on our Twitter and Facebook.

Links to our Black Friday analyzes from previous years: 2017, 2018, 2019

Thanks a lot for reading!

David Barton
David Barton
Apifier since 2016 so learned about web scraping and automation from the experts. MSc in Computer Science from TCD. Former game designer and newspaper production manager. Now Head of Content at Apify.

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