There are a lot of explanations of consequentialism and utilitarianism out there, but not a lot of persuasive essays trying to convert people. I would like to fill that gap with a pro-consequentialist FAQ. The target audience is people who are intelligent but may not have a strong philosophy background or have thought about this matter too much before (ie it's not intended to solve every single problem or be up to the usual standards of discussion on LW).
I have a draft up at http://www.raikoth.net/consequentialism.html (yes, I have since realized the background is horrible, and changing it is on my list of things to do). Feedback would be appreciated, especially from non-consequentialists and non-philosophers since they're the target audience.
In the case of prostitution, similar arguments apply to some extent to all jobs, but "to some extent" refers to very different degree.
My test would be as follows: ask how much people would have to be paid before they would be willing to take the job (in preference to a job of some arbitrary but fixed level of income and distastefulness) Compare that amount to the price that the job actually gets in a free market. The higher the ratio gets, the worse the moral hazard.
I would expect both prostitution and being a gladiator to score especially low in this regard.