I am past going to nightclubs but 35 years ago it was difficult to tell if a girl was 15 or 18, as time has gone on and the girls mature sooner and are even more aware Iam sure it is very difficult for a man.
Going up to a girl and asking 'are you older than 15' is not the best chat up line.
That young girl Mandy Smith? who went with Teddy Sherringham all those years ago, looked a lot older than her age (i think she was barely 16)