I can second Kim at Utopia... actually she's probably the nastiest dirty talker that I've encountered, and you'd NEVER guess it by looking at her... especially when she's wearing her glasses...
The thing with dirty talk is that I'm never sure if it's a YMMV thing, so I'm always afraid to discuss it in a review...
All I can say is that I LOVE dirty talk and the girls I've tried it with respond well to it, although the "physical" aspect of the session is always the same...
IE>> R & T...
Just coz I'm saying to her that I'm gonna f*ck her in the ass and make her suck it afterwards doesn't mean that it's actually happened, but you know how some idiots will misinterpret a post ...