the full-contact method

"Spotsylvania County's practice of allowing detectives to receive sexual services in prostitution cases has exploded across the nation... [Sheriff] Smith and the county's chief prosecutor, Commonwealth's Attorney William F. Neely, defended the tactic. They said detectives needed to go beyond striking verbal deals of sex for money because the "masseuses," whom they called "illegal aliens," spoke little English and Virginia's prostitution laws require more than "mere touching" to make a case... Smith and Neely said that undercover officers often purchase illegal drugs to build cases against dealers and that the "same lawful investigative technique" was used in the prostitution cases."

soliciting and receiving sex in an investigation of sex work isn't like buying drugs... it's like buying drugs, and then shooting up with the dealer to make sure the drugs are real.