I think I've been pretty lucky in my life in that the few opportunities I had to really cheat, I didn't realize I had the opportunity until the moment had passed. Or the cheating scheme seemed so blatantly obvious that I figured there's no way I (or anyone else) could get away with it. Of course, in the latter situations, the cheaters ultimately almost never got caught -- leading me to stop placing much value in my professors' observation skills.
1) I'm a little slow -- if you have a great scheme, why not just come out and explain it to me in detail.
2) If your scheme is so great, why did you have to explain it to me in such detail? There's no way that would work; it's too complicated.
Needless to say, I rarely get approached anymore with a "foolproof" plan for getting a better grade, earning "free" money, etc. My annoying qualities keep me in high moral standing.
One of my friends on the other hand seems to be presented with shady offers all the time. Most often lately, this happens with work colleagues, sometimes even at work. Apparently there's a whole slew of people that actually run side businesses (some not quite legal) while "working" at their primary job during business hours.
I'm sure this happens at my company too, but my perceived inability to comprehend shady dealings has insulated me pretty well. Incompetence is also my negotiating strategy: ask Hannah how many times I've bought jewelry at lower prices just by saying, "Hmmmm..." and pausing for a minute after being told the price. Either the jeweler thinks, "This guy's a really good haggler," or, more likely, "I feel sorry for how dumb this guy is; all I did was tell him a number and he's trying to figure out what it means... I'll sell it to him for less."
I believe in karma. Eventually, cheating is going to come back around. You might have the nicer car or the race trophy, but eventually you're going to wind up losing: either your job, your money or your friends.