Yeah, the opportunity to use the term 'perfidy' seldom comes up, so when it does you must seize it!

I've played a host of tabletop RPG's, and D&D really isn't any different than any other game when it comes to the constant struggle between the Gamemaster's plans and the players' knack for breaking them (and yes, having if-this/then-that plans ahead of time sure helps). I think some of our worst story/encounter derailments or cheesing actually happened more often in our Call of Cthulhu and Shadowrun games than D&D...