How open are to flirting with the opposite gender?

I would hope so, since flirting is probably one of the initial stages of letting someone you know you are interested in them. However, it also depends on situation. If you are already with someone and its a serious relationship, then flirting with someone else is considered a bit of a no-no, unless you want to hurt the other person's feeling (unless the partner doesn't mind).

I don't initiate it ever but if someone flirts with me and they are not irritating or unbearably ugly then I will flirt back.

Yes, flirting is acceptable... Only if you're single. I, myself, am open to flirting with the opposite gender. I dislike it occasionally because I do it too much sometimes. Don't get me wrong, I get pleasant reactions back, more of a reciprocal behavior, but I don't like how I can be sexual while flirting with certain guys. I believe it's due so according to their body language and what comes out of their mouth, which gives me the green light to push my pedal.

Of course it is. That's what heightens the attraction. Not only is it fun but it is also a great way to get those sparks flying and to check to see if they could even be sparks in the first place.

nope.

yes. I enjoy it. But I'd only flirt if I liked the guy. Guys who are only friends I might whip out a dirty joke or tease but I wouldn't flirt physically.

attention is the female's blood.

Im pretty open to it, especially since I like women ;)