I hate country and western, but thanks to FalloutNV, I've really grown to love Marty Robbins' "Big Iron".
All my life I also thought I hated metal, but now I'm discovering symphonic black metal thanks to Dimmu Borgir, and it turns out I like it a lot.
I've so far not found any exceptions to my hatred of hip hop though. Except maybe New Zealand hip hop, but that's just because it's really funny in a Kiwi accent.