Thornir Alekeg
Albatross!
I think the DM should "cheat" in some circumstances. Lets face it, the DM is already metagaming just be creating (or choosing) an adventure and planning encounters. A good DM will try and balance the majority of encounters for his party. It fun to sometimes have encounters where the party mows right through the opponents or where the party should run away becasue they are obvioulsy outclassed, but not all the time. It is not always easy to balance an encounter, and when I find that I screwed up and what was supposed to be a climactic battle suddenly looks like its going to be a cakewalk, or when it apparent that I underestimated the challenge and the party is going to get its butt handed to them, I "cheat". I may increase the HP of the foe, I may provide "reinforcements" to one side or the other, I may suddenly contrive an escape route for the party that I had not prepared beforehand (its up to them whether they use it). I do not consider myself to be cheating in these circumstances, I consider myself to be the storyteller doing a quick rewrite to make the game more fun and interesting.