I'll only use a guide if I'm completely stuck. As in, running around for hours beating my head against a wall and I just can't figure something out. I've never been and probably never will be enough of a masochist to continue playing something if I'm not having any fun just for the sake of doing it. I know once I reach that point, I'll either use a guide to get passed where I'm stuck or I'll quit the game in frustration.
I've quit games before completing them too many times in the past for that very reason, and I try not to allow that to happen anymore. Games are too expensive these days for that.