My reply to this entire thread:

Since this "jump the shark" thing doesn't hold true for my examples, the "begining of the end" for artists were:

U2 - Pop
My modern musical tastes were born and raised on U2 (and Sting/Police). Thus, when Aucthung Baby came out, I did not accept it. It Zooropa coming out to make me appreciate Aucthung Baby. And it took Pop coming out to make me accept Zooropa. (and, of course, the latest one rocks, no doubt). U2 WAS the leading edge of the music industry (no pun, the edge). It just took me a while to catch up.

Rush - they've still got it!
I haven't heard Vapor Trails, but the only Rush album I don't like is Power Windows (sorry Tony, it's too theatrically dramatic for me). Like U2, Rush innovates their sound, yes, every 4 albums. Luckily, I like each innovation.

Metallica - as soon as they picked up a guitar.
Never liked 'em. Talk about trying to be dramatic.

Smashing Pumpkins - awesome till the end!
Sure, Adore didn't have a drummer, but it was still as good a listen as any. Honestly, Siamese Dream is at the bottom of my Pumpkins stack. It was "too hard" for me when it came out.

Cranberries - Faithful Departed - agreed with yn0t_

REM - Monster - agreed with Dylan

my contribution:

Green Day - Dookie
Sure, it was decent, and it fit the pattern of them singing songs about their lives, but it was the sell-out; the begining of the end. I've never heard a band conTINUE to drag their feet for SO long after biting the dust. And never have I heard a CONSUMER community so gobble up a band putting out junk just because MTV calls them "punk". Good thing they finally broke up. (but, ya'll are entitled to your own opinions, of course. )

Sting - 10 Sumners Tales
Yeah, it's a good album, but it's the tip of the iceberg for the rest of his overly over produced, "little bit 'a country, little bit 'a pop" albums.

Delerium - Chimera
<to the artists> Ok boys, two albums of candy techno was good enough. What happened to the good old days of their like 10 interestingly ambient techno discs?

Bad Religion - No Substance
My favorite band ever (hey, ONE of them had to be my favorite), but please, "The End of the Millenium Address" was just a bit pompous. They could at least SING the lyrics like they always did. Don't even get me started on "Hopeless Housewife" and "Hippy Killers" etc.