I've seen schizophrenic homeless wandering the streets of Philadelphia a few years ago, and I can honestly say that they didn't give me the impression of intelligence, nor did I find them the least bit attractive. Though their mental condition could have been masking immense intelligence levels, and the maggots, piss, and dirt covering their bodies could have been hiding any level of attractiveness, though I'm not very partial to be attracted to old men.

It really all comes down to perspective. There is no way to clearly identify somebody's intelligence based off of exterior (or interior) observation. The only way to know for sure if somebody is intelligent or not is to deny them the privilege to use the bathroom, and observe how long it takes them to soil themselves.