I was actually wondering this the other day. If I knew what traits to look for, I would have more courage to go and talk to that person if I was quite sure if she had AS. Most of them are good at blending in.
For years, I tried to make friends, and couldn't. and the last few years, I tried but miserably failed one after another on-line. I even joined Plenty Of Fish and OK Cupid, looking for a friendships, relationships and just people to hang out with. Most girls on dating sites are mean (as well as in the off-line world), they judge people and they're too greedy. They get on and expect to find someone with good looks, money etc. It is actually very common for average or below average guys to not have much luck on dating sites. I don't log into them anymore, because they just made my depression come back.
Most NT people are the same around here. When I was i high school (04-07), pretty much everyone had the same personality. The like to drink and get wasted every weekend, party, do drugs etc. They are rude and don't care. I'm the opposite of all that. Which is why I hate NT people, because they mostly all are so much a like, and for the odd person out, like me do not stand a chance at all. If only "society" would accept people for who they are, and give them a chance before they judge, the world would be better off.
Aspies, on the other hand, often have an interesting personalities. They don't do what must NT people do, such as drugs, getting drunk a lot etc. I am compatible with most of them. Knowing, that someone had Autism/Asperger's, would probably increase my chances of making a friend (but there's no guarantee). I have been hurt by many NT people over the years, and I don't even try to make friends anymore. I know that it's the same result over and over again, no matter what I do.