redz, I know what you mean. I used to flirt with customers at my last job. It was fun, and great for sales. But it was just meant to be harmless ego-stroking. I never did it if they came in with a female partner, and if they were gay men shopping together, I flirted with both so if they were a couple no one had to feel put out. Usually, even shoppers not attracted to me (het women and gay dudes, and straight dudes who just were not into me) understood that I was just being playful, and took it in stride.
A lot of times wives or girlfriends would show up just as we were heading to the cashier and shut down my sale. every once in a while, some dude would ask me out after they were done shopping. I'd confess to being married which didn't deter most of them. Those were always awkward moments for me, and I'd stop flirting with anyone for a bit afterward. But flirting is so fun and giggle-inducing that cessation was never permanent. Plus, happy, giggly people spend more money on frivolous shit, and I did have my stats to consider.
But (outside a swinger venue) I never flirt in front of my Dude, and I never knowingly flirt with anyone in front of his or her SO. (Scratch that. I will flirt with a woman in front of her husband unless her response indicates I should stop.)