playBunny:   Ahhh, I see it now.  I used to play in an online chess league and the organizers knew there was cheating going on.  So one fellow developed a piece of software that could detect the cheating by running the suspected games through the program.  In every case the offender denied the charges.  But when pressed on and on, they confessed.  I was surprised as to how accurate this little program was in finding the cheats.

When I suspected cheating, I'd try to engage them in a bit of theory and see how well they could hold up to that.  When they couldn't explain their ideas, I knew something was not right.