I can detect it in people who I know, or I can tell the differences between someone being socially awkward and someone just being a trouble-maker. Most NTs who don't understand about socially awkwardness tend to assume a lot of socially awkward people are trouble-makers, but I can detect when somebody's not intentionally causing trouble and when somebody is. It's called empathy, I have it, NTs don't.
I can't detect other Aspies if I don't know them, unless they're doing something that's physically common in Autistics like rocking backwards and forwards in public or covering their ears or having some sort of a meltdown or something, but otherwise if an Aspie passes me in the street and is just walking along like everyone else then I wouldn't recognise anything, even if they're walking with a funny posture I still wouldn't assume they're an Aspie because that's just overestimating, and not all NTs have a perfect posture either, I've seen people walk hunched or stiffly or whatever, posture can come from personality traits too.
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