There are no bad genres, only bad bands/artists. To dismiss an entire genre of music is as bad as dismissing entire genres of films, books, or any other art form. There are great rap/hip-hop acts. There are great country singers. There are great metal bands. Etc. etc.
The idea of "I hate [insert genre here]" is juvenile at best, willfully stupid at worst.
Reading all the replies and just wanna say that just because a genre doesn't appeal to you isn't a legitimate reason for hating it. Id rather read a reply from someone who listens to it all rather than most of you who only listen to one or two genres and writes off the other ones.