Everyone's given really good advice above. I can't really improve on it but here's my two ha'ppen'orth anyway.
I love being teased but even with people with whom I really "click" and with whom I've talked/role-played/bantered for literally years, sometimes they will say something inadvertently which just kind of turns me off or even spoils the mood I was in, or even has the potential to upset me (were I to take it seriously or think it was meant in any way meanly). It can happen to anyone, depending on the exact way someone is feeling that second of that day. I can enjoy a certain kind of teasing one day but not be into it another - maybe I'm not feeling so good about myself or I'm more sensitive than usual. Or they could just use one word - one fairly inoffensive, silly word - that just makes me think "ugh, I hate that word." It's not their fault and they don't mean to upset me or shatter the carefully-concocted pretence that we've set up, but it sometimes just happens.
Equally the person being teased has a responsibility. The teaser is kind of going out on a limb for you, saying potentially offensive things that could be really badly misconstrued, just for your pleasure and erotic fun. So it's your duty, I think, if you're the person being teased, to be as clear as possible (and often repeated, because the teaser may need reassurance it's still ok and it's still working for you) about what turns you on and what's a definite no-no. Tell them when you enjoy something, respond clearly to what they're saying, even if it's only an emoticon or a "mmmmm", maybe join in with the narrative or swing it a certain way that would make it even better for you, guide them a little.
Sometimes remember it's not all about you and if you can, play along with something you know they find really hot (if it's neutral to you, I mean, not if it's making you cry into your keyboard).
Even if you don't really buy into all the stuff they like, sometimes you can do a hella good job "faking it" to the point of feeling quite satisfied with the effect you've produced in them... after all, they are probably sometimes giving you stuff that aren't 100% their cup of tea too. Sometimes I just love talking filth to people on subjects I know they really dig, even though I'm virtually unmoved by them, teasing them about stuff they love, and by the end of it and they've had a good time and got all worked up into a froth about how hot it is, I'm thinking, hell I am DAMN good at pushing that guy's buttons, that was FUN. (As long, I guess, as you're not pretending you're having superfunsexytimes too and they know you're just humouring them). Yeah, on reflection maybe that one only works with people you know pretty well. Ha.
The more you learn about each other's preferences as you go along, the better it may get. Equally don't be afraid when you're comfortable with someone to throw something random or new into the mix - if they know and trust you and it doesn't work, it won't matter, they're not gonna go running away yelling "mean pervert!" because the other half of the time it probably does work and they're grateful/turned on by being shown something new.
It's all communication and I'm hardly the person that gets it right even half the time myself - just don't be discouraged, keep at it, and enjoy