Why is prostitution criminal and/or public?

The governor of New York has apparently been caught being involved in a prostitution ring, and will likely end up resigning.

Secularists often state that sexual morality is private, and should be kept separate from public life - who's hurt when a man pays for sex?

Answer: Sexual conduct is not private. The basis of solid society is a public sexual relationship - between man and wife. The state rightly publicly recognises such relationships, and not others (a man can't marry a boy (yet!)). If the state publicly approves of one sort of sexual relationship, then it must be definition be disapproving of others. To say that sexual conduct is private and the state can't be involved is a position which logically leads to sexual anarchy. If the state can't disapprove of prostitution, then there's no logical stopping ground before we say that it can't disapprove of the man-boy love league, or a man marrying three wives and two husbands, or a goat. If sex is just about personal preference, then your preferences are just as good as anyone else's, no matter how perverted. Secularists can't have your cake and eat it. I've spent a bit of time criticising the state for poking its nose into things that aren't its business - but sex is its business.

New York governor Eliot Spitzer made a public vow, recognised by the state, to forsake all others except his wife. When a man flangrantly breaks such a vow, he can't suddenly claim that it's not public after all.