I agree that 'hate' is a word little too strong to describe the feeling, but...
From classical...
I can't stand Fantasie Impromptu by you-know-who.
Hearing the 18th variation of Rachmaninow's Paganini Rhapsody makes me want to be somewhere else.
Volodos' transcription of Mozart's Turkish March sounds too much like the whole point of the piece is lost, can't appreciate it.
Couperin's excessive use of trills tires my ears out, physically.
Some orchestral arrangement of Liszt's 2nd Hungarian Rhapsody was pretty silly and made the piece sound... ummm... ghey.
Xenakis' earbreaker pieces... break my ears.
I really can't say its comfortable to listen to certain Cziffra's recordings, they literally hurt my ears. Too bad, because I love his interpretations.
Arvo Pärt. I've only heard a piece or two from him that appeal to me. The rest sounds empty.
Some Messiaen sounds like chromatically improvised nonsense trying to keep the listener active by freaking them out with loud noises once in a while.
I think Rachmaninow's playing sounds dry, especially in contrast to his technical virtuousity. The guy hated performing, so I guess one could expect to hear it.
From other genres:
Avril Lavigne. Hahah I didn't even know who she was, or was supposed to be, until recently, but I already hate her.

Rap with meaningless lyrics and uninteresting rhythmics. What a total waste of potent form of expression.
"Soul" pop music. Hahahahaha, this one makes me crack up. I'm talking about female pop-icons or whatever they like to title themselves, singing in a slow fashion on pointless electronic backgrounds, trying to compensate the shallowness of the musical content by trying to appear as if they're expressing deep emotion and thought by phrasing melody and lyrics in slightly off-rhythm emphasises, as if they're making heavy points on each occasion.
All the generated pop music that plays on radio and TV. Pop-rock. Rock used to be about breaking rules and freeing the mind, or something. Now, "rock" is just stuck up in methods and patterns, and needs a new "rock" phenomenon to revolutionize it. Distortion effect used to be handled with taste, now it is only abused to create background noise to purposelly drive a song into certain level of dissonance to cover up the actual melodic-harmonic dissonances that the piece fundamentally possesses. Cheap. This music really is bad for ears.
Generally, movie soundtracks are often surprisingly blank when taken out of the context. Somebody, having seen a movie, plays some movie soundtrack to me - I'm like "That's nice. Doesn't sound wrong. Doesn't sound especially interesting either, though." -People don't always realize how much of the power of music in movies or games is based on associations between their other senses and memory that brings them all together in an even more perfect form. I don't hate film music, just thought this was an interesting realization.