I think that in so many ways we are wired to not stop. I often saw people who got numerous lets say romantic conquests and they motto seemed to be a number's game. Ask as many times as often as possible until someone would say yes. Or keep on asking while somehow being cute or nice.

In a similar way, I remember when I was younger and I tried sales for a little while and they told us, "Don't stop until you hear three 'no.'" And it seemed that the three 'no' rule was not out of respect of the potential client but out of the sake of not continuing wasting our time. As a client I've been on the other side of the desk hoping the other person will stop asking out of respect (?) or out of need (here in the US after you buy a car they will try to sell you all kinds of insurances and upgrades and what not).

My point is that the system is geared towards harassment and it is difficult to know what a legitimate interaction is. Of course, now I am an old man full of doubts and I rather not talk much to no one and all I can hope is not to intrude too much. Which is probably as unhealthy as the first stance.