I have animation turned off, so not only do I not use animated icons, I don't even see them.

If an icon is text that looks incomplete or makes no sense, I guess that it's animated. If the first image in the animation makes sense in itself, I may never realize that there are other things behind there.

Conversely, there's one person whose journal I read on my friends list, and the first time I tried looking at it by itself, with her background and such, I hurriedly hit the "back" button--she has it set with some kind of moving background that Firefox doesn't treat as animation-to-disable and that flickers in ways I really don't like.