These polls are useless unless you also post 5 underrated bands to put things in perspective.
That said (in no particular order):
Overrated:
Underrated:
No particular order but three that I don’t like, don’t understand why other people DO like and I find them to be just too damn preachy and self-righteous (which is really the deal-killer):
U2
REM
Midnight Oil
You make me jealous that I didn’t put them on my list.
Heh.
Lists like these are actually quite useful to help identify the character foibles of the people who generate them. 
You have to be specific here because you’re talking about at least 3 different bands (effectively) which all shared the same name. KC I I would argue belongs in the overrated category, coasting for about 6 years on the momentum of their audacious debut. KC II (1980-c. 1985) would certainly be underrated, as the progheads pretty much ignored what they were doing by then, as did mainstream rock radio, and they didn’t exactly fit into any of the postpunk genres very well either. III (2 1/2 if you like) I don’t know what to do with tho; I guess by then they have shared the fate of all post mid-90’s bands who pretty much are absent from both our threads here.
Honorable Mention: The Who
Extremely Popular Band Who Most Critics Actually Recognize as Shite, So Maybe Can’t Really Be Called “Overrated”: The Eagles
That is dead on. Kudos.
The Doors. As already mentioned, they are the most boring band ever, no exceptions.
Nirvana. If Kurt Cobain hadn’t killed himself, they’d be a forgotten one-hit wonder. Everybody would remember “Smells Like Teen Spirit,” but most people would blank on the band’s name.
The Grateful Dead. Deadheads still rave over them because they just can’t face the fact that they wasted their youth following around a mediocre band while tripping on LSD.
KISS. They were supposed to be the epitome of heavy metal Eeeeevil[sup]TM[/sup], but now as I sit back and listen to “Detroit Rock City” and “Rock and Roll All Night” on my mp3 player, I know that it was just a huge publicity gimmick, and there really wasn’t anything edgy or daring about them at all. I still like those songs, tho.
Rolling Stones. I think that most people only go to see this band because they can’t stop staring at Mick Jagger’s freakishly large mouth.
This is an interesting point. Please go ahead and start that thread.
Grateful Dead.
A strong contender here, Rush, is one of my fave bands. The thing with Rush is, they’re the quintessential musician’s band. I very rarely meet a non-musician who’s into Rush, and no longer expect to (I also meet lots of musicians who hate Rush).
I (a casual hobby bassist) was instantly hooked by Geddy Lee’s inventive, aggressive, bold bass lines as well as Neil Peart’s drumming. Hearing ‘Moving Pictures’ for the first time, I was blown away by the band’s sound and style. Extremely rich and colourful, yet sparse and precise (huh?). Techno-rock. I’ve never heard anything like it since. I could listen to that one album all day long. Not because of beautiful melodies or hooky choruses, or though-provoking lyrics or heart-wrenching feel or what have you. The wackier the better!
Seeing the band pull off all their chops live only cements the awe I feel for those guys. They are extremely skillful and highly original musicians. I can enjoy that in the same way I enjoy looking at a fine piece of exotic furniture handmade by a top-notch woodworker. I can relate to the huge amount of work, the perseverance and the talent behind the work. I couldn’t care less if the artwork is pretentious, overblown or overproduced. I feel most popular music in every genre is boring, safe, plagiarized dreck - like a blockbuster movie where you know all the time what will happen next. Not a big worry with Rush.
Underrated by who? Every Metalhead I know (admittedly people in their thirties and up) swears by Black Sabbath. A nice way to get into a fistfight is to say “Black Sabbath aren’t the originators of Heavy Metal” or Black Sabbath isn’t the most important Metal band of all time". Even guys who don’t listen to old music much at all feel obligated to bow their heads to Iommi & Co, IME.
I have to go with that, and I love Mott the Hoople.
There are so many that it’s hard to choose.
I might as well post my reply to the Pit because the thought that some of these groups are popular or highly regarded makes me angry. I don’t know how I’m going to control myself.
5. Radiohead - A lot of people mention that this band has done nothing since OK Computer, but, OK Computer wasn’t even that good. It had two listenable songs, and the rest were given a pass because they were a bit different sounding. They are often described (somehow with a straight face) as “atmospheric” which is just a fancy way of saying they aren’t worth actively listening to. In other words, turn them on and play them in the background because you’ll get more enjoyment out of their music if you do something else and don’t listen to it. Radiohead is the musical equivalent of a soft breeze being called a hurricane. Completely forgettable.
4. Red Hot Chili Peppers - They have exactly one song. It’s uber-repetitive (seriously, listen to their songs, they repeat the same line at least twenty times in every song they play) and it’s about California. That this band got to make a second album is a travesty.
3. The Rolling Stones - I’m shocked that this band was ever considered good. I think they lose points because they keep parading around on stage in a mockery of their own crafted image and refuse to hang it up, but then, that assumes they ever earned points to begin with.
**2. The Beatles - **You don’t ever hear people going around saying that the Backstreet Boys are the greatest musical group of all time, do you? So why do the Beatles get so much love? How are they different? They get points for being a musical “sensation,” (which is to say, basically, that they were popular) but their library is a bunch of shallow noise with little communicative depth. They were the Backstreet Boys of their time. While the Beatles could play instruments, the Backstreet Boys could dance, so it’s a complete wash. Beatles love is embarrassing.
1. Bob Dylan - The single worst popular “musician” in the history of recorded music. Whereas every overrated group I’ve mentioned has at least the lingering odor of redeeming musical value, Bob Dylan has none. He can’t sing. His widely hailed and near-universally-regarded lyrics are essentially bad poetry inundated with palpable pretension. Moreso than being completely, unequivocally, worthless to listen to, Bob Dylan’s stink attracts entirely the same type of personality. Anyone who claims to love Bob Dylan is going to be exactly the same as every other Bob Dylan fan, and it’s a safe bet that they can be ignored without fear of missing out on anything interesting. Bob Dylan is so bad that appreciation of his “music” is actually a black mark on your personality.
The Grateful Dead
Phish
John Mayer
Bob Dylan
Mariah Carey
Kiss - mediocrity disguised as edgy
The Doors - save me from the keyboard!
Grateful Dead - chemically enhanced mediocrity
U2 - all their songs sound alike. But kudos to Bono for trying to save the world.
Garth Brooks - okay, he’s not rock, but he’s overrated, and I can’t think of 5