Seems a no-brainer, but it is sometimes hard to remember when you’re designing a game. The players (and by that, I mean “the people playing the game”, not “non-GM participants”) aren’t out to subvert what you do. They’ve bought your game, they’ve bought into the idea of it, they are gathered together to try to play and have fun. They are not trying to use loopholes to make the game not-fun.
I was reminded of this when reading a post over on Vincent Baker’s blog from a bit over a year ago, Reliable vs. Unreliable Currency. The post itself is not really what caught my attention, but rather the comments, Ben Lehman’s especially. He talks about sportsmanship, that magical thing that lets a group of people working towards a common goal (fun, good story), but with competing interests (their characters’ desires), not forget the former for the latter.