"Most experienced Dungeon Masters will probably already have a proud repertoire of clever and innovative (not to mention unique and astounding) artifices, deceptions, conundrums, and sundry tricks which will put to shame the humble offering which follows. Nonetheless, this enumeration might serve for those who have not yet had the experience and seasoning necessary to invent more clever devices to bring consternation to overbold and incautious characters" (Gygax, 1979, p. 216).
Most often I feel that tricks are not my responsibility as DM. I am not big on traps either. I have had terrible experiences, terrible, where the neat thing had to be figured out by the players before success or progress could be had. The DM does not help when he or she chides the players for not getting the right or desired answer. What is that chiding good for? Is it my job to teach the players to be careful, with real-world advice? Shouldn't my description of an area or thing be enough to suggest that something is dangerous or difficult?
But JoMo, what about the monster's point of view? Surely the monster wouldn't want characters to get through certain areas. Well, it seems to me that such contests of wit would be as difficult as guessing someone's email password. Unless figuring out the oh so clever trick can be resolved by brute force, there does not seem a good use for the monster's point of view regarding tricks. Even then.
I also think it is lazy to say that puzzles and such are there because the boss monster at the end of the dungeon only wants the smartest minds to get through. Yes, the Mind Flayer sits waiting for only the juiciest brains to come. That's great, thanks. Let's just face that the DM wants to give the game a twist that is different from combat and traps. I challenge my fellow DMs to do better.
Gygax, G. (1979). Advanced Dungeons and Dragons: dungeon masters guide. T.S.R.