"Fortunately" it also auto-translated the "I happily accept the terms of use" checkbox in one case into (back-translated) "I happily dying die perish", which also couldn't be clicked. That lead to a very high priority ticket and made us realize that all DOM manipulators might break the site.
Got a bug report from one of our own team members that some of her greeting cards didn't show up in the list. The link appeared, but no image. We figured out that the difference was she was running an ad-blocker. We couldn't figure out precisely what rule the blocker was applying, but it seemed to be:
- image
- within some particular size bounds
- with the consecutive letters 'ad' in the URL.
... and we were using hexadecimal encodings to track individual entities in the UI.
We solved the problem by replacing 'a' with 'g' in our hex encoding. And then I had to take a long walk and accept that if I was going to do web development on the public Internet, I'd be sharing the space with intentionally-modified user agents forever, and would have to account for every such modification as we discovered it.
I still won't run my own ad-blocker for this reason.
I maintained an extension for a public website for a couple years. (It did things like, for example, adding information that was available in the API to the page, for power users.) I eventually gave up with the conclusion that the concept of a browser extension was fundamentally unsound. So I also don’t use an-blocker.