Everyone has varying degrees of ability in different areas.
Some people are sensitive to non-verbal signals, and some less sensitive, and some really have to work at understanding them.
People who genuinely have Asperger do not realize there is such a thing as non-verbal communication until someone teaches them. Their instinctive understanding of human nature does not even include it.
Ironically, their abilities and temperament are actually highly prized in a great many employment situations.
It's job searching where they're handicapped.