So you've just met a girl on the beach walking your dog, and you've been chatting for say 20 seconds and everything is going smoothly so far. But you’re also kind of thinking that the small talk is due to wrap up shortly. So my choice is that I can blurt out the idea of us going on a date now... without having built enough rapport. Or I can continue talking using my conversation skills to their full potential while assuming that we’ll most likely part and never meet again. If I think I have to ask her out I’ll be just looking at her thinking “will I make my move or not?” and not be relaxed.

I suppose one way would be to see how long she's willing to just stand around talking to a stranger and if it goes beyond 2 minutes then she can't act surprised that you asked her out. If it were a movie, we'd part ways but accidentally bump into each other later!