I wasn't suggesting real time 'no, fuck you' DM dickery. That's just a power trip, and another example of the GM failing at their job.
I was stating that if the GM designs encounters he knows the players can solve, especially with a single use of an obvious mechanical ability, then either that was supposed to be trivially easy, or the GM fucked up. You still have to roll with it in the context of a game, i.e. you don't make it un-happen, but you still made a mistake. The point of encounters/challenges is that they are challenging, otherwise why have them?
in b4 basket burner - this still means that if you make the challenge too hard, i.e. basically unsolvable, you have ALSO failed as a GM. As I keep fucking saying to Roy, just because before you optimized the creature with gear, feats, skills, buffs, terrain and tactics it was the same CR as the party, that doesn't mean it's an easy encounter.
EDIT: Basket Burner (christ that name sounds dumb), I agree that it is possible in DnD to make a character that is incapable of performing nearly any action, or of defeating any kind of encounter. I've never seen a character like that, though. What I have seen is a lot of 'weak' characters that through clever play completely outperformed vastly mechanically stronger characters. And i've seen a lot of literalist GMs who when confronted with a player being clever block that player, or simply ask for a skill check. There's nothing quite so wretched as watching a GM try to justify a NPC doing something that's not in his best interest or character simply because a player didn't hit a specific diplomacy check DC. Or watching a GM whose NPC/monster was just outwitted by a player's smart move suddenly go and patrol the room the player concealed themselves in or go 'on guard' in a doorway that clearly wasn't going to be guarded until the player avoided the GM's encounter.
Competent DMs adjust the strength of their encounters to the party, and creativity and cunning is not 'how you build your character's trip attack to have infinite bonuses and never fail'. In this context, that's actually the opposite of the meaning, as you're optimizing a mechanical solution to the whole problem of 'combat' that means you don't have to be creative to solve the problem at all. You might initially be creative in adding the numbers together or using a combination of abilities, but it's not creativity in context of the game, just creativity in the context of the game's rules.