Chapter 14: Sneaking

In the ‘reverse pyramid’ style of writing, we are taught to be helpful to the reader by starting off with a short summary of what’s to come, followed by progressive layers of detail. The idea is that this enables the reader to stop reading at any time and still have an accurate impression of the article. If you want to manipulate the user, you can do the opposite and sneak key information into long paragraphs or poorly labelled sections, so that readers are unlikely to expect it or seek it out. With user interface design, there are many more opportunities to use sneaking, given all the different forms of interaction available: scrolling, progressive disclosure (where the user can click or hover to reveal content on the page), links, buttons, and so forth.1 In commercial transactions, it can be profitable to hide information, as you can see in the three types of the sneaking deceptive pattern explained below.

The sneak into basket deceptive pattern

There are several different ways an online retailer could sneak things into a customer’s basket. The most brazen approach is to just put it in without mentioning it, and hope the customer either doesn’t notice or doesn’t care enough to complain. It’s also possible to use misdirection and other deceptive patterns to trick users into inadvertently adding items to their basket themselves.

Sneak into basket by Sports Direct: an unwanted £1 magazine

A few years ago, Sports Direct was famous for its giant promotional coffee mugs that everyone in the UK seemed to have in their kitchen cupboards. Let’s look at why. Below are screenshots of the website taken in 2015.

Let’s imagine I’m happily browsing the website, about to buy a pair of walking boots. As you can see, there’s nothing weird going on. It’s just a regular shopping page.2

Screenshot of a product page for walking boots. On the left is the product image; in the centre is product information, including the price of £184.99.
A product detail page on in 2015.

Now, let’s say I want to buy these boots. I choose my size, click ‘add to bag’ and then proceed to the checkout.3 See anything strange?

Screenshot of a checkout page listing the contents of an online shopping basket. As well as the walking boots selected earlier, a magazine and mug have been added to the basket. The total price is £185.99.
The checkout page on in 2015. An item has been added without the user’s consent.

In a line below the walking boots, there’s now an item that I didn’t put into my own shopping basket: a magazine and mug together for £1. Sports Direct was called out for this on Watchdog, a popular BBC consumer rights TV show in the UK. In 2014 this practice became illegal in the EU, thanks to the Consumer Rights Directive.4

The hidden costs deceptive pattern

The practice of introducing hidden costs (also known as ‘drip pricing’5 or ‘bait and switch’6) involves intentionally introducing a price increase that the user isn’t expecting in the buying journey. More often than not, this manifests as unexpected fees and charges on the final checkout page, immediately prior to paying.

Hidden costs by StubHub

An excellent example of hidden costs was published in a research paper written by researchers Blake et al. in collaboration with StubHub (the entertainment ticket reseller) in Marketing Science journal in April 2021.7 The paper is well worth reading, since StubHub seemed to be strangely proud of their own deceptive practices. Be warned though, the paper does use euphemisms extensively. For example, instead of talking about hidden costs, it refers to ‘back-end fees’.

Here’s a visual example of the StubHub user experience. To summarise, the price you see at the beginning of your shopping experience is lower than the price you see at the end; and that’s after you’ve been forced to input your full name, phone number, email and postal address.8

Two screenshots of an online ticket purchase experience. In the first, one ticket has been selected and text on the site says ‘You’ll pay $310 each’. In the second, after the user has entered their name, phone number, email and postal address, further charges have been added, now totalling $401.13 for the same purchase.
Screenshots of the different prices that StubHub shows for a ticket (1) at the beginning of a user’s journey and (2) at the end.

In their research, Blake et al. did an A/B test comparing (A) a design that used hidden costs that were only revealed at the very end (see above) against (B) a design that showed accurate costs at the very start of the user journey. They collected data from several million transactions and it’s probably the largest A/B test of deceptive patterns ever published.

Guess what happened. The users in group A who weren’t shown the ticket fees upfront spent about 21% more money and were 14.1% more likely to complete a purchase. That’s huge.

So, now imagine what it would be like to run a business and know that one simple design decision would get your customers to spend 21% more. It’s a no brainer – of course you would. One of the only things that would stop you is the threat of legal consequences that would cost more than the profit you’d get from it.

Hidden costs by Airbnb

Resort fees, amenity fees, destination fees and cleaning fees have been common in the hospitality industry for a while. In 2019 Marriott charged cleaning fees of up to 55% of the listed booking price.9 This behaviour led to them being sued, and the ensuing legal process revealed some staggering internal documents. Marriott knew from its own internal market research that guests were very concerned with the ‘lack of transparency’ in fees, but they proceeded with it anyway, earning more than $220 million from this practice. An audit also revealed that 33% of the time, resort fees were not shown at the time of booking – the customers only learned about them afterwards! Marriott eventually settled and the company does not engage in this practice any more.10

It’s not a great case study without any visual examples, so let’s move on to Airbnb. For some time now, Airbnb customers have complained on Twitter about additional fees, as you can see below.11

Screenshot from Twitter showing a tweet from user alexa, who tweets ‘we gotta stop airbnb’ and includes a screenshot listing fees above the $198.00 price originally shown. There is an additional ‘cleaning fee’ of $114, a ‘service fee’ of $44.05, and ‘occupancy taxes and fees’ of $57.90, bringing the total to $413.95, more than twice the cost first shown to the user.
Twitter user alexa complains about Airbnb’s additional fees. Her post was popular, with over 200K likes from other Twitter users.

The key question here is whether the fees were hidden at the outset of the user’s journey, or whether users like alexa (above) were told in advance but were just unhappy about the high price. The specifics are a little hard to pin down, since Airbnb runs different versions of its user interface in different countries, and it makes regular changes over time. However, these screenshots show what it was like in the United States, around June 2021.12

In the screenshot below, you can see a user has selected to travel to Mexico City between 13 and 16 July with two guests. You can see on the map there’s a range of...

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Since 2010, Harry Brignull has dedicated his career to understanding and exposing the techniques that are employed to exploit users online, known as “deceptive patterns” or “dark patterns”. He is credited with coining a number of the terms that are now popularly used in this research area, and is the founder of the website He has worked as an expert witness on a number of cases, including Nichols v. Noom Inc. ($56 million settlement), and FTC v. Publishers Clearing House LLC ($18.5 million settlement). Harry is also an accomplished user experience practitioner, having worked for organisations that include Smart Pension, Spotify, Pearson, HMRC, and the Telegraph newspaper.