Prostitution (and drugs) should be legal (however, I don't partake in either). It is a personal responsibility issue. For "The State" to dictate what I do in my own home (or with a consenting adult) so long as I don't hurt anyone else is an infringement on my freedom.
Prostitution is the "world's oldest profession" for a reason and it isn't going away. You can now shop for a call girl online and as an earlier poster mentioned, it's now a business (a friend of mine worked vice and they just googled "Escort" and the city). Even an "average" call girl can make minimum of $5k a month with 20 johns (yet another reason for scrapping the current tax system and going to a national sales tax).
I'd suggest for those of you that believe government should be the moral arbiters of society, that you worry more about what goes on in your home and less about what goes on in your neighbor's home.