I agree with Sue: if you don't need him, pass. Neither your "instinct" nor your observations will tell you if he is or is not someone who will be motivated to try to harm you. Ted Bundy is a good examply - but AFIK very few such monsters looked scary enough to raise concern among their victims. I've read numerous "profiles", and I don't believe your observations regarding whether he looks like a choir boy or a creep would be much help.

Therefore you must assess his capacity to harm you. And your capacity to defend yourself. And the risk of injury even if you sucessfully defend yourself. And the risk if you don't take the risk... and go off on you own.