I do think a girl who looks like a stereotypical playboy bunny can charge more. It's not that a lot of men will think "Oh, I'll pay more for her than for that more average girl" - it's more a matter of such a girl will have a lot more guys wanting to book. So, she can raise her rates and thin the herd a bit that way. If a girl is regularly turning away business because she's got all the bookings she can handle, then it makes sense to raise rates and such a girl would likely have a great many potential clients. If a girl has 15 enquiries a day, and she only wants to see three or four clients, and out of those fifteen a handful will pay more, then she will do well to raise her rates.
I think quite a few men won't pay above a certain price, so maybe not many would stretch to pay for Ms. Bunny, but she would still get guys who are willing to pay more, in general.
What I don't think is particularly the case is a woman considered less conventionally attractive needing to charge less. I don't think too many men think "Well, I can only afford X amount so I guess I have to settle for this lady, here." I'm sure there are men who think like that but it wouldn't be a very pleasant experience for them to shag someone they didn't fancy just because it's all they can afford.