Inspiré de http://darkpatterns.org/
While filling in a form you respond to a question that tricks you into giving an answer you didn't intend. When glanced upon quickly the question appears to ask one thing, but when read carefully it asks another thing entirely.
You attempt to purchase something, but somewhere in the purchasing journey the site sneaks an additional item into your basket, often through the use of an opt-out radio button or checkbox on a prior page.
You set out to do one thing, but a different, undesirable thing happens instead. During 2016, users of earlier versions of Windows where shown pop-up windows similar to that pictured above. As the year progressed, Microsoft became increasingly aggressive with the pop-ups. They started as an honest, optional call to action, but became increasingly deceptive. They switched the meaning of the “X” button at the top right to mean the opposite of what it normally means. In all other versions of Windows going back to the 1980s, this button means “close”. In this specific instance, they changed it to mean “Yes, I do want to upgrade my computer to Windows 10”. This caused a huge public backlash.
When your free trial with a service comes to an end and your credit card silently starts getting charged without any warning. In some cases this is made even worse by making it difficult to cancel the membership.