I won't date, much less have sex with, a woman that isn't intelligent.
The "problem" with sex and intelligent women is that they require more...and get this...variation. You can't just keep going with missionary and doggy-style.
This really applies to all women, but maybe intelligent women are more demanding.
Additionally, you can also up the intensity. I guarantee to that, even if I'm going at her doggy-style, she won't be bored if I'm pulling her hair and using enough for to dislocate a leg.