While many covers suck I don't mind the ones where the band/musician takes a song and makes it their own instead of trying to basically copy the original. For example take a pop song and turn it into a metal song...
I have to agree with Geoff on this as there are no bands that I really hate...quite a few that I don't want to listen to though...stuff like Taylor Swift( although she is easy on the eyes) and most pop music today....
I will agree with you about Vain and while No Respect is their best release, I rarely play it and it would not make my top 100 as I find it rather average.....