ExploderWizard
Hero
Well as far as making saving throws and other rolls. Me and our other DM's have been in the practice of making passive rolls for the playera already anyway. And we also make dummy rolls to throw em off. But my issue is with the situational effects that are unlikely to go off because the enemy isn't stupid enough to trigger them. Alot of these can be explained within the context of the game. I guess the fighters mark was a bad example in that sense. The enemy knows he's been challenged and the negative effects are pseudo-morale based for not meeting that challenge. But there are other effects that I think the enemy shouldn't be aware of, at least until they're triggered. Or maybe some other way of getting that metagame knowledge in-game. Like a spellcraft check or something, depending on the type of effect. I just think that having a rule that states that all creatures, automatically know everything about what is effecting them is too big of a catch-all. It doesn't allow for those surprises.
I don't have a problem from with concealing effects from the players provided they are not affected directly. If an NPC spellcaster puts up a globe of invulnerability there is no need to announce this fact. If a player asks and has the required skills then there is a chance of finding out. If not then they will figure it out as events unfold perhaps.