Is prostitution legal everywhere now?

I've been frequenting Craigslist lately, looking mainly for guitars and/or playstations and/or straw hats, and I noticed a section for "erotic services". Now maybe I'm completely misinterpreting what these services are, but they appear to be prostitution. Seems like if this was illegal, it would be pretty easy for the government to shut down as every ad has a phone number in it. Do they just not care enough? Or are these "services" something different?

Edit: oh, and don't open those ads up at work