That's an odd question.
It depends on what you consider to be flirting, if you mean just holding a polite conversation with just about anyone... that is a powerful type of flirting.
Just the other night I met this natural 'DJ'. He walked into the bar like everyone was already his friend, he saw my friend who most would probably rate 8-9 out of 10, and he wanted to hit on her. He came up to us and just started a regular conversation, then there was this table of asian girls sitting behind us, 'you want me to get you with that girl.' He pointed to this girl on the dancefloor that I wouldn't have wanted to maintain. 'Well, have you ever had asian before, I haven't myself.' No, so he turned back to the asians again and starts telling them my name, and this and that and everything. I knew from the start that he wanted to flirt with my friend, and I saw that he knew the score as well so I wasn't about to stop the guy (I am disinterested in the girl, I know her too well.)
But, I always tease cashiers, just chat up absolutely anybody if I sense that its worth asking for the numbers I keep in touch with just about anybody if they seem straight up. Once they start acting shadey, I just stop calling... simple. Most girls love it. Some are simply unnapproachable... keep in mind that the less of an 'agenda' that you have the more likeable you become.