This is usually hit or miss situation especially if its done to cash in on their 20sec of fame:
I've always dug Tom Waits a actor ever since I saw him in Bram Stocker's Dracula and Down By Law.
Iggy was great in Dead Man and Crybaby
Gene Simmons is a pretty decent villain especially in Wanted: Dead Or Alive
Wendy O. Williams (RIP :( ) was fuckin' dope in Reform School Girls
I haven't braved watching my Cradle Of Fear DVD yet :p