The key, according to veterans like Amy, a 32-year-old model/actress who has had happy ending massages in two different states, is clear but subtle communication: "It's all about giving the right signals." She first discovered erotic massage during an in-room rubdown at an upscale Miami hotel. "Initially [the masseur] kept it very clean, but I was really turned on, and I let him know it by moaning and saying how good it felt. He started slowly touching my thigh, then going higher, and it turned into a game of how far each of us would take it. One thing led to another and he ended up finishing me off, which was great."

Occasionally, a spa’s reputation for sensual goings-on will precede it, as with New York City’s famed 10th Street Russian Baths. An East Village fixture famous for its massive steam rooms and "women only" days, it once drew celebrities from John Belushi to Frank Sinatra and now attracts a cross section of New Yorkers from Russian sexagenarians to downtown fashionistas.

"At first you're on your stomach, so they're just massaging your back," said Trish, a 29-year-old marketing manager who frequents the Baths. "Then they turn you over, and [my masseur] started massaging my breasts. My nipples got erect, so that must have sent him a signal. He started rubbing me on the pressure points around my hips. I was wearing bikini bottoms, and he never actually touched my clitoris or vagina; it was just all around the area. I did [have an orgasm]; afterwards, people kept stopping me on the street to say, 'Oh my God, you're glowing.'"

Chemistry with your masseur is a key factor, and one that can’t always be controlled. But if it’s present, the possibilities are endless. "I was going through a divorce and feeling like hell," said Alexa, a 30-year-old attorney. “So I went to a high-end spa for a massage, and the only person available was a guy—I was nervous, I’d never had a man massage me before. He ended up being so hot. I was turned on the whole time, but nothing happened. Then I went back two weeks later. I was on my stomach while he massaged my back, and when I turned around, topless, we started making out. He said, 'I can't do this, it's unprofessional,' so we stopped. But when I went back a third time, we ended up having sex in the massage room. After that, we started dating.”

Nonetheless, it’s important to remember that the risks can be high for massage therapists. Every state (save Nevada and Rhode Island) considers prostitution illegal, and in some states it can lead to months of jail time. Also upping the ante is the gray area surrounding sexual assault, generally defined as nonconsensual touching of the genital area.