First - Johnny Cash could sing a cover of anything and make it sound good. The man covered songs by Bono, Nick Cave, Bobby Darin, Bob Dylan, Kris Kristofferson, John Lennon, Trent Reznor, Paul Simon, Bruce Springsteen, and Hank Williams.
Second - I like bands like Big Daddy, Dred Zeppelin, and Me First & the Gimme-Gimme’s that cover well-known songs in a completely different style than the original. I’ve heard there’s a band called the Red Stripes that does reggae covers of White Stripes’ songs, but I haven’t been able to get a copy.
Covers are…interesting. At least, they should be. I don’t know if this counts as a cover, but Prince’s version and Sinead O’Connor’s version of “Nothing Compares 2 U” are both very good, but in such different ways. One is pure, ethereal pain, and the other is deep in your guts, grinding pain (guess which is which :D). They are the same song, but both belong in the pantheon of rock songs in their own right.
As for interesting covers, Dwight Yoakam has an album of covers out (called Under the Covers) that is unbelievably good. It has a bluegrass version of The Clash’s Train in Vain on it that works, somehow. That Dwight, he’s got some big cojones (which he likes to show off, but that’s not important right now).
I tend to agree with Pulykamell - as I do on a lot of music stuff:
the concept of a “cover” is a recent, rock phenomenon. Until the modern era of recording, the main way for the vast majority of people to hear a piece of music was to hear someone other than the original writer to play it. Same with legends and books: Until books came along, the only way stories were told were via the village storytellers. The nuance and interpretation added by an individual was considered part of the art of the story - having books come along and set “the standard” for a story took a long time for cultures to adjust to and was resisted.
However, even back then with songs - some folks are good interpreters of songs and some aren’t. Some songs have a lot to give to alternate interpretations, and some don’t. And some songs are accessible to an audience that is open to multiple interpretations, and some aren’t.
I love an interesting cover - when a good interpreter takes a good song and opens my mind to different possibilities. I do go into that situation expecting that the vast majority will not be as good - just like I suspect that the majority of jazz players doing a jazz standard like “Salt Peanuts” won’t approach Dizzy Gillespie or the majority of classical players won’t do a version of “Ode to Joy” comparable to the Vienna Symphony. Such is life…
As a musician, having a song move from a single, canonized version to becoming a standard would be incredibly flattering. The fact that Yesterday has been covered by hundreds (thousands?) of artists has to speak to the bullet-proof amazingness of the song unto itself. The fact that 99.9% of the versions might stink doesn’t take away from the song…