I think so - generally speaking.
I have a very simple tactic when it comes to this situation and I can't say I've had to use it as of late. When I see the woman/girl in question hitting on the man/guy I'm with (with - not necessarily dating) I'll smile, introduce myself, check her out head to toe and ask the guy I'm with if we take her home to play with tonight.
Never, ever failed.
.....ever.
Heh.