It took two CCTV exposés to prompt Guangdong officials to crack down on the sex trade in Dongguan, but the city has been a hotbed of vice for years.
Once an industrial hub of the Pearl River Delta, the sex trade took off as its exports began to lose steam in 2009.
Video: Dongguan prostitution exposed by CCTV
Despite occasional crackdowns, business thrived, and the term "Dongguan-style" even made its ways into the lexicon of the prostitution business.
Before the financial crisis, businessmen from the mainland and overseas thronged the more than 100 swank hotels spread across the city, cutting deals with the delta's many manufacturers. But when contracts dried up, no one had a reason to visit.
"Average occupancy rates of high-end hotels have dropped to between 30 and 40 per cent," said Bob Yao, who has connections to Dongguan's sex operators. "They don't care what kind of business you do inside the hotels."
A night's stay in a two-bed deluxe room at the Silverland Hotel, the city's oldest five-star hotel, costs about 250 yuan (HK$320).
Women factory workers - some laid off, others who left willingly - provide the service.
"A young prostitute can get between 100 and 500 yuan for each transaction. It's easy for them to make between 20,000 and 50,000 yuan a month," Yao said. "Sex hotels are everywhere. If a female migrant worker lost her job at a factory, she could join the industry."
Dali Wang, a hotel manager in Dalang township who is familiar with the sex industry, estimated the city had as many as 250,000 prostitutes at one time.
Previous crackdowns only forced hoteliers and syndicate operators to bribe more powerful officials for protection.
The underground trade grew so formalised in recent years some insiders boasted about the uniformity in how prostitutes were trained and money distributed among various parties.
"It's called the Dongguan-style ISO standard and is well-known among all Chinese pimps," Wang said, referring to the International Organisation for Standardisation.
Part of the appeal for patrons was they knew what they were getting, Wang said.
"Clients feel safe in Dongguan," he said. "They don't need to worry about being victims of a scam or a game at the hotels. Most high-end hotels will even pay and bribe officials to set guests free if they are caught at the hotel during police raids."
Dividing up the profits was also well organised. "For example, if the customer pays 800 yuan, the girl gets 300 or 400, and the pimp 50, while the hotel operator gets the rest and 200 yuan is reserved to bribe officials," Wang said.
"Higher-end hotels have stronger networks of senior authorities, from police station heads to senior officials at the municipal or provincial level."
Despite the latest crackdown, the trade may return, Wang said.
"It's a big blow to Dongguan but we might see it come back unless they can root out bribes to officials or close the hotels."
Video: CCTV news report on sex trade in Dongguan