I think it's all a matter of personal opinion. I talk to almost everyone I come in contact with. It's part of my nature and also part of my job. I waited tables all through college, so I had to chat people up. Now I'm a nurse, and I have to chat people up because they're usually naked and I want to distract them. My dad is a natural born talker, too. He knows everyone, everywhere! I swear, he ought to run for public office. I get it honest!
Dh on the other hand, doesn't talk to strangers much. He usually stands behind me and rolls his eyes or laughs at me. He cuts up and makes jokes with women he knows, but I've haven't seen him flirt with someone since before he and I started dating. It's just not in his nature. He doesn't mind if I talk to strangers, flirt with a bartender, etc....he'll just make fun of me now.
As a once professional flirter (young, blonde, southern, sorority girl) I have a pretty good handle on what I consider flirty, and also when someone steps over the line. I will also call them out on it.
DD is just overreacting, I think because of her age. I was just curious what others consider flirting. Some people get jealous very easily and don't want their SO even looking at others, while others could care less. Well, I care, but I can't say anything about looking or I'd be a hypocrite. 
I agree that teenagers aren't always the best judges about parents and flirting, etc. When DH gave me a quick peck on the cheek 
walking into church, DSD14 accused us of "making out in church" 
and mortifying her and making her sick. 
