Military Photos.net for several reasons, among them a moderating staff and numerous members that piss and shit on everyone else and break out into calling people "retards" and shit for the littlest, stupidest things.
Resident Evil Forums (actual name) because of a fuckwit member who likes insulting everyone who disagrees with him and a headcase admin who thinks he owns everyone on the site and can tell them what websites they can and can't visit. Headcase admin even had the audacity to tell me that I had to leave the forum I started and come back to his or a forum war (whatever the hell that is) was on. Needless to say, I tracked down his YouTube account and told him to suck my "RPG".

Last I heard, the place had died down significantly after I left due to the most prominent members following me to my forum.