My last visit to Dongguan, China's widely acknowledged and often acclaimed prostitution capital, was in 2011 (for a factory visit) and included a breakfast meeting at a well-known U.S. chain hotel, in view of the elevators that whisk customers to their rooms.

Over eggs, my companions and I watched as those elevators discharged a flood of young women, one after the other yawning and rubbing their eyes, clad in the previous night's high-cut dresses. Not one stopped for breakfast or to settle room charges at the front desk. They simply sashayed out the revolving doors and into Dongguan's smog.

More than likely these young ladies were representative of the 500,000 to 800,000 prostitutes who Chinese media estimate worked in Dongguan up until 9 p.m. on Feb. 9, when authorities launched an unexpected crackdown on the city's thriving but still illegal (prostitution has been illegal in China since 1949) sex trade.