I can't believe someone else posted the 3-date rule.
I always felt that if a guy was bright and fun and there was no "compelling aversion," that it would take at least 3 dates to get to know him enough to see if there is a spark.
Year's ago a co-worker posed just about the same question as the OP, and I told her about my three-date rule. She is now happily married with a daughter, and she says it is all because of me.
DH and I hit it off from the start, but I used to have a thing about guys with lots of hair, and he was balding. But I liked him so much that I forgot all about that silliness. We were engaged within a year and will celebrate our 6th anniversary in October--and I still feel like a honeymooner.
The more you like a person, the better looking he or she becomes.
Good luck!