Creepy people date too.
What generally makes someone “creepy” is when there is some incongruity between how they present themselves and what their actual motives and interests appear to be. Often it is just a subconscious impression that the person is being dishonest or hiding something. For example, a perfect stranger who appears overly friendly and talkative. Immediately I’m like what does this person want? Why is he trying so hard to ingraciate himself to me? He could just be a lonely person who is a bit too forward. Or he could be someone who is trying to gain my confidence and trust for some nefarious purpose.