What I found was that, yes, it's legal in some counties in Nevada, but not in Las Vegas, Reno, Carson City, or Lake Tahoe (i.e., the only places in Nevada that anyone has ever heard of). This site has a fascinating FAQ from a regular John - and, I should warn you, that's an adult-only type of link. It covers pretty much everything you ever wanted to know: how much does it cost? How does it work? Are the girls attractive? Are they nice? Do they actually like this job? Do they kiss on the lips? (Apparently not.) Etc.
This page, and most others from the look of them, didn't mention male prostitution at all. So I did a search on the legality of being a gigolo, and learned that (according to at least one site) a man can't legally be a prostitute anywhere in the States. How unfair is that? Come on! Affirmative action!
Sorry, ladies, guess we'll have to wait until they actually create a Gigolo Joe.