There are many ways to ID them if you’ve been around them any time at all...education, background, vocations, languages they speak and their mannerisms...and the pat answers they provide but start asking very detailed questions hey haven’t thought of the answers or and you can have a little fun...: )
I was not only around one, I was boinking her. :)
Another giveaway — she was a mild mannered school librarian, but ran rooming houses she owned. She seemed to be energized by any extreme activity — conflicts with tenants, moving their stuff out surreptitiously, engagements with police (including one time we gave some cops the slip). She thrived on it.
Odd, for a meek little suburban librarian. :)