For me I watch and listen and see how long they have been a member. Nothing is fool proof. But if I see a new member always hinting around or asking , I shy away from that. Others have been here awhile and you know more about their background.
Some ask, ask, ask and never acknowledge that they have received anything publicly , like they don't want you to know how much they have already received.
Others post as soon as they receive something to say THANK YOU .
It is a trust thing and you just hope for honesty.