Some guy asked me recently how you can IOD without looking like you're being a reactive little bitch.
There are different levels of IOI, there are different levels of IOD (indicator of disinterest). "You're a bitch and a cock-tease" is a pretty strong one, and, as you point out, something like that is going to come across as pretty reactionary! An IOD that'll make you look bitter is one that looks like you're having an emotional reaction to her, or is out of proportion. So what can you do?
My all-time favourite one is to pull that little involuntary twitch of "shit, she fucked up" that you'd use if she accidently made a huge faux-pas - it's a really subtle expression, but we've all done it before naturally in other situations - reverse-engineer it. You don't want to be getting back in to Cocky/Funny or hardcore negs once you're at a certain part of the sarge, or you're moving backwards. I think, in practice, I'd most likely have rolled my eyes theatrically (IOD, but not a reactionary one) and befriended the guy (DHV).
Something else to consider here is something that
Juggler teaches, when he's talking about what (I think) he calls 'hooks'. This is where you embed something interesting in the conversation (like: "haha, reminds me of the time I saved an orphan from 16 maurading sharks"

), and then move on straight away afterwards, rather than looking expectantly at the person.
Mystery calls this 'throw and go' when he's talking about negs. Delivering negs 'expectantly' and woodenly is a common mistake guys make, without even realising it, and it looks totally chodish and reactionary. Negs should be fun, light-hearted - one I use a lot is "don't look at me like that, my mother looks at me like that!". It's not even mildly insulting, so it's hard to do it wrong (and with my tendency to drink heavily, that's important)
Hope this is useful!
-sheriff