Metal, its generally pretentious has hell, nowhere near as heavy as it thinks it is and the lyrics, well the lyrics are just plain embarrassing. Obviously there's exceptions, doom metal is awesome, and theres the odd tech death and thrash bands I like, but overall its not a genre I would want to associate with.
Nerdcore. Yeah, I just said I hate nerdcore on a gaming forum. But seriously the novelty of white guys who can't rap over terrible beats wears offer after the first 20 seconds. I like nerdy references in rap, stuff like Doctor Octagon, but when its all someone is rapping about its boring.
New dubstep. Srsly what is this shit, dubstep used to be an amazing genre full of speaker blowingly heavy sub bass lines, now its just lots of mid range noise.
Indie rock. Bit of a vague term to use, but I mean more specifically those generic indie bands from the UK like The Enemy and The Wombats with their shitty regional accents and their shitty lyrics about drinking and birds and their shitty haircuts. Uninspired, boring crap.
Acoustic. Again too much of a vague term to use, some acoustic stuff like Rodrigo Y Gabriella is amazing, but those acoustic singer songwriters who make bland music for bland people, who have one single then disappear for ever, they're awful.