Never used cheat codes, I don't see the point. Only time I've done it was for extra lives in the original Rayman, because that game is brilliant but impossible. I used the 99 lives code 3 times and still only got to the 4th zone. Madness.
I occasionally use walkthroughs if I'm really stuck, or near the end of a game to see if there's any large sidequests I've missed before polishing off the final boss.
Wait... unless
photographing a half-solved Picross puzzle when the timer's about to run out so I can reset the timer and redraw the whole thing counts
Lol I'd forgotten about that.