I once played a really shitty conman.

In a dystopian society, there was a resistance. The resistance required weapons. My character, whose name I forget, was an arms dealer. Mr. Arms Dealer sold them broken and shoddy goods (making himself an appallingly wealthy man), and generally sabotaged them at every opportunity just so he could sell them more.

He was doing this completely openly, because the dystopian society knew he was draining the resistance's resources and the resistance had nobody else to turn to.

He pales in comparison to the monsters in this thread, but maybe I'm such an angel I can't write people that appalling... :3