This varies by game of course (as does everything else in this thread) but I think I can be specific about what I object to: when the game has rules that force characters to react in certain ways (fear, charm, lie detection, etc.) but then the GM also thinks that in other situations the characters "should" act in similar ways. That's the line that I don't like to see crossed.
Take sleep. I have fallen asleep during movies, at concerts (the symphony sort, not the rock sort), in lecture halls, while I'm supposed to be keeping an eye on the baby, etc. Clearly dull content can put me to sleep, with no magic required. And while roleplaying I might respond to a GM description of a scene by having my character fall asleep, especially if there were something about that character that would suggest they would be especially bored by the context. But I would object to the GM requiring me to roll to stay awake in response to an NPC trying to bore me to sleep, simply because "in real life really boring things sometimes put people to sleep."