I have a few more to add.
Hendrix: I appreciate that he's talented, but his music is boring to me.
David Bowie: Ziggy is pretty good, Fame is awesome. Other than that, nah.
Black Sabbath: I think they're incredibly overrated and I'm a metal guy. Ozzy's voice is annoying and Sabbath is basically early Doom Metal. Slow, heavy and boring. He became much better when he went solo, but still overrated.
Slayer: As a thrash fan, I find them very overrated. They're fast, but that's about it. No melody and Araya's voice is very generic thrash sounding. Kreator, Testament, Megadeth, Metallica, Anthrax, Death Angel, Exodus, Sodom, Onslaught and many others are better.
The Sex Pistols: Boring and uninspired. Nothing else to say here.
Guns n' Roses: One of the most overrated bands of all time Seriously, they have 1 DECENT album. Why was everyone so surprised when Chinese Democracy came out and everyone agreed the wait wasn't worth it? Hm...perhaps GnR just wasn't as "great" as you remembered?