I think a lot of people are confused about the topic.
There is a difference between not liking a band and being underwhelmed (yes, I know its not a word) by them. Its not interesting to have people sit here and talk about what bands they hate. Its more interesting to hear about people actually liking a genre or style of music in general, yet feeling unimpressed by a sucessful band that plays within that genre.
For example, someone might like Nirvana and Soundgarden but think Pearl Jam are a bunch of hacks.
I don't mind people saying they don't like the Beatles, that they're not interested in their sort of music, but calling them overrated (which implies that they believe this in spite of some interest and knowledge of rock/pop/60s music) is just plain bizarre.
That said, I don't want to draw this argument out.