[quote=@Lucius Cypher]
I could make a character who's S in Intelligence but that doesn't mean squat if I myself can't solve a simple riddle. Mental stuff is best left to solo authors since he can easily feed the answers to his character because they're "Smart", but you can't really do the same for characters you don't directly control.
[/quote]
There's also the issue of a smart player trying to play a dumb character--maybe it's not as difficult as the reverse, but I've already brainstormed a couple of scenarios with my character, Kenichi, where I suddenly realized "No, it wouldn't really make sense for him to do that because he wouldn't have access to that information like I do." That's a problem that always comes up in regards to Meta knowledge, but it also accounts for a person trying to write a character below their own intelligence level--we might have known something for so long, or it might have come so easily to us, that when other people [i]don't[/i] have that level of knowledge we're surprised--"I thought everybody learned that?" The end result, for authors who aren't careful to double-check what they've written, is a character who is [i]supposed[/i] to be dumb somehow either outdoing people smarter than they are, or causing a character who's supposed to be average to have to up their intelligence to genius level, and the genius has to now do tenth dimensional equations in order to keep their title.