Guitar_Whizz
Master Don Juan
No, not true. Not all girls give non verbal signals to guys they find attractive while out in public. Maybe they're shy, maybe they're in hurry to get somewhere, got thing on their mind etc.Blindly trying to pick up a girl who's never showed sexual attraction signals is a waste of time and effort.
While a guy should be tuned into non verbal signs from women, and be ready to act on them, he should also NOT wait around for these exclusively. He should approach whoever he finds attractive and take his shot.
That is my mindset and my experience - I do not wait around for women to give me signs they want me to approach (especially here in the UK where people can be a bit closed off to strangers). I simply approach whoever I find attractive. I go direct, never indirect. I've had plenty of success with girls who never gave me any 'signals' to approach.
A guy will lose out on a lot of potential girlfriends or hook ups if he only approaches those who give him signs first. That said, for shyer guys who are not as boldly confident as me, then you can approach only those who gives non-verbally signs. But once you master the cold, direct approach you boldly go for whichever girls you want!