I am certain that this is true.
I already know the traits\symptoms, notice people avoiding eye contact, recognize when someone goes on about an unusual special interests, and can tall when people's body language is off due to a lack of understanding. I also find that if I feel on the same wavelength as someone else, there is a good chance they are not neurotypical.
One big clue is that I find that I am always sort of bridging the gap between how different people communicate (there is MUCH more variety than NT vs ASD). For example, if I feel insulted by what someone says or does, I try to take it into the context of this person's overall behavior. Maybe they were not taught formal manners, maybe they just have a certain sense of humor, maybe they take certain cultural things for granted, etc. The same for within the context of a group dynamic. For example, in most male-dominant social groups, insults\teasing are a form of bonding and not meant in a mean way. Different cultures have different ways of expressing things. I am always bridging the gap in good faith.
What I find is that there are some people who also seem to be much more willing and able to bridge gaps in communication than others. I often find that if someone is particularly willing (if not able), then there is a good chance it is because they are divergent in some way and do so out of necessity.