What is "Dongguan Characteristic" and why Dongguan is the sex capital?

In Dongguan, the "sex capital" of China, there are about 300,000 people who "100,000 ladies go to Lingnan and millions of prostitutes go to Dongguan", which is a very popular joke. Dongguan is a new city with manufacturing industry, and it is rumored to be an ambiguous entertainment paradise. People who come to Dongguan often receive a short message: Tell you that Dongguan is your dream gentle town. Dongguan's ambiguous service has also formulated a set of "Dongguan-style standards"-known as "ISO". As we all know, "ISO900" is a famous quality certification system. Behind the "universal standard" is a huge and complex erotic industrial chain. The so-called "urban spirit" in Dongguan is "generous and pragmatic, and all rivers run into the sea". Indeed, all rivers flow into the sea. Due to the developed manufacturing industry, a large number of migrants have flooded into Dongguan, and the total population of Dongguan has exceeded 6,543,800+million. There are hundreds of people, all kinds. Of course, among so many people, the main body is engaged in manufacturing, but without the service industry, the erotic service of the service industry will "escape". On the one hand, lonely migrant workers, as well as investors and gold diggers from home and abroad, want to "consume" various "entertainment services"; And many women workers who came down from the production line directly entered the sex service industry. Dongguan is even called the "sex capital" of China, and the folk saying is "300,000 prostitutes".