I know I shouldn't, but some avatars just make me hate the poster without even knowing anything about them.
This avatar:
, as an example. I don't know anything about the poster and for all I know he/she is a good, decent human being. But it hurts my eyes a bit when I focus on it and kind of pisses me off. It's just a fucking picture, but any time I see them posting I'm automatically predisposed to read whatever they post in a negative light.
This avatar: