With women, I am accused of flirting far, far more often than I do so deliberately. I assume either that I'm an incorrigible flirt, or easily misinterpreted in that direction.
With men? I'm not often taken to be flirting with men.
In either case, I tend to be the innocent party when another flirts with me. Usually, I won't even notice. On such occasions as I am receptive to flirting advances, I become shy and abashed quite quickly, though I've seldom acted to discourage the behavior. Now that I'm married, of course, this doesn't come up much. I try to bear in mind that I may be seen as flirting by others, but my flirting has always been unambitious even when deliberate. It's just how I talk.