1. Kid Rock never should have did Bad Company's "Feel Like Making Love". He took something beautiful and turned it into what easily could have an advertisement for sex shops. His version had nothing to do with love, and I would so love to see Paul Rodgers beat the crap out of the Kid and teach him not to mess with the old school stuff, imo.
2.Foo Fighters never should have did Pink Floyd's "Have A Cigar". Pink Floyd were masters at what they did, and nobody can cover them and make it sound right, imo.
3.Dave Grohl was right to do Prince's "Darling Nikki". I never knew the man could scream like that until I heard this. Somewhere deep inside, Dave has got metal in him that's just dying to come out, and I say, "bring it on Dave"
4.3 Doors Down was right to do Lynyrd Skynyrd's "That Smell". They did not try to make it their song; but instead, paid the utmost respect to the mighty Skynyrd, because they have got a perfect match, note for note.
But, then again, I am a huge fan of 3 Doors Down, so I might be just a tad prejudiced here

"I find it kind of funny.
I find it kind of sad.
The dreams in which I'm dying
Are the best I've ever had."