You definitely see this dynamic in Supernatural. I mean, neither one of those guys could ever pass for "nerdy" but it's always been Sam who's been portrayed as the more intellectual one while Dean is the sort of dumbass who relies more on brawn and luck than brains. I thought this was even more noticeable in the first few seasons when Sam was still carrying around his college-boy vibe. There are times that both of them seem so dense that it's a miracle they aren't dead yet but it's usually Dean wearing the duhhh expression on his pretty, pretty face.