Yeah,
Your initial appearance wasn't good enough.
It's just a polite way of saying fvck off I'm not interested in you.
They would have talked and gigled with a really good looking axe murder/rapist and invited him home.
To answer your question another way, with a question/rebuttal.
Yeah, I sort of understand what your saying, and can you remember the last time you met someone you didn't know, and they turned out to be an absolutely amazing, warm, interesting person?
The idea is more to get them to think about that person and suddenly they realise that everyone's a stranger until you get to know them.
If you get a no. I'd tell them they need to get out more.
Don't forget the initial eye contact and body language. All the non-verbal attraction stuff. This is more important than anything as you are less likely to get rejected before you even open your mouth.
You can also do some C&F like, yeah, mammy always told you not to talk to strangers, I just thought you were a big girl now that's all. (smile)
or
Well, as you can see I haven't got those hangups.