There is a time to flirt, and a time not to flirt I believe.
I am very flirtatious by nature, but I try to tone it down if I'm in a relationship.
I work at Olive Garden as a waiter, so flirting with a wide age spectrum of women, from hotties my age to grandmas is kind of necessary if I want to get a phatter than average tip. If you're waiting tables, flirting is being professional.