i usually don't really respond. it just depends. i've become immune to random encounters now. i'm more of a guy that reacts to genuine interactions, not the occasional eye-batting, smiling and glances thrown my way. i come in contact so much of that flirtatious attitude, there's no point in responding to it unless some more effort is applied. the last time i can remember really responding to a random woman showing interest in me was about a month ago. and the only reason why i did was because she started questioning me (which is what i prefer anyways) about myself. that's what i appreciate, women that are actually trying to get to know me. women that are just trying to fukk are a whole other ball game. that's when i start becoming picky because i don't need to fukk them. either i want to or don't. and the reason i'm connecting women that send out vibes with women that are trying to fukk is because of the environment i'm in where it happens (it mostly happens when i'm playing, like a good 9 out of 10 times). those women are women that want something from you, or women that are trying to take away something from you. they flirt, but in the end, they just want to get fukked. that's not to say that i wouldn't, but it's draining to just come in contact with women that are, clearly, only about getting their clits tickled (no offense to other females). the reason why it's tiring is because it's always the same story, same approach, nothing unique about it. most of the interaction lacks honesty.
so, my typical reaction is a nonchalant one. and i do it out of necessity. also, you start to realize that women don't have that much (if any) "game" when you're placed in situations like that...