I guess, in a way, exploiting the AI of a fighting game is cheating...in which case I'm guilty as sin.
But it's hard to see that as cheating when the AI fighters can be so cheap. Increased damage, impossibly quick reflexes, input-reading, super-unfair attacks (Gill, I'm looking at you)...crap like that gives me no choice but to find a hole in the AI and exploit it.
Oh, and that damn microscope puzzle from The 7th Guest. Got to the point where I didn't even bother anymore and just used the clue book in the library to skip it.