How did I manage to miss this thread until today?
Anyway...from my experience 99.9% of the time the ones asking for extra pics (usually a nude, I show my face) dont book.
Now, you still have that 0.1% who will book and I have had it happen. When I first started and didnt want to show nude, I had a client tell me they wanted to see some nude pics of me, which I did. I also had another guy ask me for some nude pics to "get him going" and I did. And I met with both of em. But thats just a narrow exception. Very, very narrow.
Otherwise, my site has everything they need to see and can go there. I say, "I dont send out extra pics, what you see on there is all me". It doesnt do any good to even say that as then they dont respond (like Ani said)
I noticed once I featured nudes on my site I get less emails asking to see, which is the only thing the majority of the viewers want, without actually booking you.