Being a bit flirty myself, I have to agree. I've been around guys I was not interested at all in a romantic way (though perhaps in a friendly way) and didn't realize I was even being flirtatious, just thought I was having fun joking around. But then when I am intentionally flirting with a guy who I'm interested in, it used to be that if they didn't notice, I'd take it that they weren't interested and just move on; now I realize some guys just don't
notice until you outright tell them (and if they really aren't interested and say so, then it's all unambiguous and much easier on everyone).
Then again, sometimes women aren't flirting at all, but a guy who really is attracted to them sees everything they do as flirting because they are looking with blinders on. I ran into this problem with the janitor at work. Apparently not many people talk to him, so he took something as simple as me saying hi and asking how he is to be flirting. And of course his behavior changed based on that and I ended up thinking for a while he was the creepiest guy I ever met.
Anyway, it would all be so easy if people could get over their hang-ups and just tell each other outright when they're interested or not.
Though, I still don't understand getting upset worrying about women who already have boyfriends. If they constantly need to be the center of attention and nothing you do with them is right, then they are what we call "high maintenance." More trouble than it's worth.