Are Bruno Mars, Taylor Swift, Katy Perry etc. actually rated by most people, or are just well-known?
A lot of people posting this thread have overlooked that it's asking about CRITICALLY overrated music and consequently missing the mark badly. The Sex Pistols is a very good answer (although one for which the critical tide has begun to turn). So are Radiohead, The Clash, and Led Zeppelin.
Sticking to recent stuff - because I think that almost all music recorded prior to the mid '90s that hasn't faded from the collective memory is at least somewhat overrated - I'd add a few more:
M.I.A.
Vampire Weekend
Drake
Kanye West
...actually, I had a few others in mind, but that's probably enough that I'll need to hide for a while.
Do the critics
really like Led Zep? I know they didn't like 'em too much back when they were active; sure they get plenty of hagiography now but I suspect that's more a function of their historical popularity and importance more than critical taste.
I'll admit to liking Zep and Radiohead, though the critical slobbering over Kid A is certainly... less than warranted. But I feel like saying that is less a brag and more an admission that my tastes are in many ways really kind of pedestrian and whitebread.