Only one person mentioned Axl Rose? Complete and utter douche, single-handedly destroyed one of the greatest rock bands.
Gene Simmons.....he's an ass, for sure, but he also admits it.
Eddie Van Halen.....responsible for killing the greatest American rock band, and for years and years of non-productiveness. Sure, DLR is a douche, too...but EVH has also run off Sammy Hagar, whom pretty much everyone gets along with, and Gary Cherone...who, while he sucked in VH, is also a great guy. The only constant in all this is Edward. Hell, he's even fired and rehired his own brother several times.
Sebastian Bach: Total and utter douche, and not all that intelligent, from what I've seen. That Supergroup show pretty much confirmed what I thought about him. And to the poster who said they didn't know how any band could function with Sebastian in it: They don't. There's not a band with him in it. Nobody can work with him.
I don't put Bret Michaels on the list at all. He seems like a pretty good guy to me. Poison isn't serious music...it's good-time music. Absolutely nothing wrong with that. Obviously, millions still agree, since they play sold-out shows every time they tour.