This post was inspired by a story in the WaPo, the relevant detail of which is that, due to the economic hardship in Greece, some young Greek women are selling sex for the price of a sandwich they cannot otherwise afford to buy. Also, the argument I want to make may be old news; this is not a topic where I have a lot of familiarity with the literature.
There are basically two moral views about sex work, which I will define for present purposes as the exchange of money for some form of sex in short-term, one-off transactions. (So, here, sex work is prostitution.) One view is that sex work is a lot like other kinds of work, except it is mostly performed by women and, due to various kinds of sexism and discrimination, has historically been stigmatized and exploited labor. The right course is to learn to treat sex work as normal work, and enact appropriate regulation that protects the sex workers, in the same spirit one would legally protect other kinds of workers.
The other moral view, which I take to be encoded in most state laws in the US (I can’t speak for elsewhere), is that sex work is morally problematic in some deeper way. The usual thought, I believe, is that it degrades the sex worker; sex work is intrinsically undignified. The proper way to handle sex work is to proscribe it entirely, where this is practical, and in any case discourage it. What follows is an argument in favor of this general view.