I used to think that way, i.e. that flirting will give the other a false impression of yourself or that it's similar to acting. Maybe it's the introversion of INTJs that makes them think like that, but flirting must be one of the sexiest things in this world. You learn a lot about the other person through flirting. It can be hidden in the subtext of a normal conversation or the typical sexy flirting (we're nerds, aren't we?). When I flirt, I'm actually quite naughty with my language. And especially with ENTPs you really can't be "offensive" enough, tss!