DOTA games and the people who play them.
DOTA games have an absurd amount of heroes/champions, sometimes 100+, which aleady sets off alarms in my head. If you were to play each of them for 2 hours, that's 200+ hours of playtime just getting familiar with the basic playstyle and abilities of each. That doesn't even begin to touch on actually becoming comfortable or skilled with any of them.
Imagine if TF2 had 100 classes. How the fuck would you balance a game like that? Not to mention zillions of fundamentally game-changing items.
My limited experience with a dota game was when Heroes of Newerth was in beta. I didn't know much about the genre, but I figured I'd give it a try. Bumbled around a bit not knowing what I was doing, and then got yelled by some kid on my own team who had probably never seen tits before in real life, because apparently I screwed up something I didn't think was very well explained to begin with. Because that's another thing about these games, they're not big on explanations. THIS IS A DOTA GAME, YOU'RE SUPPOSED TO KNOW WHAT TO DO ALREADY, YOU STUPID SCRUB.
I have friends who are really into these games and they keep telling me they're a lot of fun and have great strategic depth, if I would just give them a chance. But I just can't get myself to give a damn. There are so many other games I can play and have fun in without having to "give them a chance", and without having to put up with what is essentially the world's largest collection of immature gamer kid stereotypes.
So yeah, I won't touch these games with a 10 foot pole.