No beef with either personally, but my sister hates Avril with a passion. Here's the story:
My sister is big into singers like P!nk and stuff. Avril seemed cool, and she liked her music for a little while--until she heard that Avril was a cheerleader at one time. Now, she calls her a poser.
Then again, I don't know where she gets her info. The only musican I really have problems with is Eminem. Music is to share emotion (and anger is a good emotion

), not to try and get shock value. (I wrote an entire essay on how censorship needs to be lowered everywhere except for music, and he was my main 'scape goat', you could say--got an A on it.)
Yay for '70s rockers!