I have always told my girls the following: Unless he has incredibly rude manners, poor hygiene, or is insufferable in some other way, give him a second chance if he wants to see you a second time. Some guys are too nervous on a first date, because they want to make a good impression, and it backfires on them. It is only when they go out again that they begin to relax a bit.
Also, someone whom you do not find attractive to you the first time around, might seem more so as you get to know him. I can tell you for a fact that I know many people (male AND female)whose looks seemed rather ordinary, but as I got to know them, I found them to be much better-looking. Beauty is in the eye of the beholder, for a reason. When we see someone’s heart and soul, their sense of humor, their hashkafa matching our own, they become infinitely more attractive in the ways that count for a lifetime relationship.
OTOH, of you absoltely cannot abide this person, don’t waste his time, either.