also these goonshttp://www.youtube.com/watch?v=ggGEWw_ocUQ
For sheer obnoxious awfulness, you can't really beat brokenCYDE:(Slightly NSFW for swearing) http://www.youtube.com/watch?v=N8F5YSA1Oz0As for mainstream groups and artists, in a competitive field, surely the Black Eyed Peas have got to be the most offensively terrible band currently operating? I should say, I don't listen to pop music if I can avoid it - it's not my cup of tea, but I can usually appreciate a good pop song and see why it is successful - not so with the BEP - I just think they're laughably bad. I'm genuinely amazed how anyone over toddler age could find anything to enjoy in their godawful music. I gather that they were once a moderately respectable hip-hop group, but all their songs since they became famous just sound like nursery rhymes for idiots.
The sad thing is Fergie from black eyed peas actually has a good voice. The tracks she does on the new Slash album are really good. Black eyed peas however are absolutely dire.