I think it's far too easy to slag on bands you hate as being "overrated" simply because they recycle previously great innovations from a pioneering forefather whose early demise ensured his own legacy would be forgotten so long as those that came after him watered down the essential grit and turned it into easy-listening claptrap that everyone in America bought into.
But enough about the Eagles ripping off Gram Parsons 
Let's be brave and list those overrated bands that you happen to like...and let's be fair, every band or artist that attains a certain amount of popularity starts to believe their own press, so it's no disrespect to hold their feet to the fire. Might help cleanse the collective memory of rock. So my candidates:
The Beatles - for Sgt. Pepper, the fact that "everyone loves them" but can barely name more than ten songs (and none of the obscure album tracks), the fact that every band that has followed has had "-mania!" attached by some overzealous journalist looking to score cred points, and the bizarre solo careers (Macca, you magnificent bastard!)
The Clash - For trying to continue after Mick Jones' forced exit, turning the freedom that punk initially offered into a certain three-chord style that other bands imitate ad nauseum on college-rock stations today (nevermind the fact that they embraced black soul and reggae, nobody thinks of that side anymore when they think of "punk" and the Clash have some blame in that).
REM - For their major-label work (not quite as invigorating as the IRS Records material), for being the poster-boys of alternative long after they were embraced by the mainstream, for the "Shiny Happy People" mess.
The Doors - For riding Jim Morrison's corpse into a misbegotten legacy that could see the former singer of the Cult try to fill the Lizard King's pants, for the mythology surrounding what was basically a second-rate poet and first-rate drunk, and for "Light My Fire" being used at some point in every single movie ever set in the 1960s, about the 1960s, or with any bearing whatsoever to the 1960s.
Belle and Sebastian - For their "fey" early recordings, which diehards cling to in the wake of their inspired turn towards mainstream pop (get over it, it's all about artistic growth).
Sex Pistols - For putting out one album before imploding, building up Sid Vicious into an idol when he was basically a hanger-on that got lucky.
The Kinks - For everything that came between Lola and Come Dancing (a bit harsh, but needed saying)
Gram Parsons - for the aforementioned cliched early death, turning to hardcore country in his solo career after blending rock and country in his work with the International Submarine Band and the Byrds, and for being basically someone that only music snobs know of :D
Eric Clapton - For going from a brilliant sideman with various groups (the Yardbirds, Cream, Bluesbreakers, Derek and the Dominoes) to an uninspring and AOR-friendly solo career 
