They don’t seem to tell. But in the beginning, the nice guy who caught her seems to be handling her rather gingerly; at first I thought she was feral...then she seemed to calm down when he started petting her.
He was a very brave guy. I’d never pick up a feral kitten without serious gloves.
I have a feral cat I’ve been feeding for a year or two. I would never ever dare to pick her up. Only pet her tail and hind quarters. She stopped hissing six months ago and I’ve heard her purr a couple of times.
p.s. Friends of Feral Felines fixed her and gave her a long term rabies shot.