I always correct people who say "could care less." If you could possibly care less about it, you care for it somewhat. If you "couldn't care less," you cannot possibly care any less about it.
I always said "couldn't" and people would correct me. Finally, I just decided it was easier to day it incorrectly so people would shut up. Don't you know the first time I said "could" to someone the jerk corrected me in a real snobby manner.