So then you hire some of those guys to come in and play test your game for you. Have them spend tons of time trying to find cheeses. Most of the cheese that exist in the game are relatively obvious if you are looking for them. Hmmm, there's a bridge I have to get across? Screw that, I'll just fly. I have to kill Phogoth? Nah, I'll just sit up here and wait for him to come out and snipe him. AOE grenades move enemies? Let's surround Atheon and see if he moves off the edge.