Let me first try to address intelligence.
Intelligence is not only relative, it is subjective. I think intelligence, though very subjective, does actually exist. Generally, I believe that intelligence is something that makes you quantifiably better than someone else at some thing. For those who think that "better" is a subjective term, notice I specified "quantifiably", which by definition makes it possible to determine what is better. For instance, if we assert that if John wins more races than Steve, we can conclude that John is a better racer (of this type of racing). The problem is that there's more to life than racing. Intelligence is a very general aspect, and it supports any ability that requires thought. What makes intelligence so subjective is that we can't simply sum all our abilities to determine who's more intelligent. The equation factors in how important a particular ability (type of intelligence) is (ability1 * importance of ability1 + ability2 * importance of ability2...), which complicates things since importance itself is subjective (very).
That being said, people have different ideas of what intelligent is, which I assume is the main point of this thread.
I think most people tend to say certain things for reasons that aren't straight-forward. People tend to say things not necessarily because it is true or accurate, but because it achieves a goal. So in this case, if a guy says he wants a girl who is intelligent, I'm assuming he has other requirements which generally exist to filter the type of girl who'd think she is applicable for his type. Which could be anything from her actually being intelligent (whatever that is), to her liking Star Wars or something equally irrelevant (yet associated).