Their victims are young, poor and often female, and usually share their ethnic backgrounds.
They are pimps and human traffickers, modern-day slave traders in a black market economy that includes Orange County mansions and whole apartment buildings in Los Angeles.
Linh Tran tries to stop them. She runs the Orange County Human Trafficking Task Force, part of the county government. On Wednesday night she spoke to the South Orange County Democratic Club at the San Juan Capistrano .
Tran said the demand for underage prostitutes is high enough in Orange County to recruit from outside the region. The young women arrive from places like Las Vegas, San Diego and Northern California, many not considering themselves victims.
"If you are a minor, under the age of 18, you are automatically seen as a sex trafficking victim and given assistance," Tran said. "Whether or not they see themselves as victims is another story."
It's big business, Tran said. She estimated that on an average week, a pimp with five prostitutes can earn $7,000 cash.
But more victims of human trafficking are bought and sold for manual labor than sex slavery here, Tran said. And many of them come from other countries.
In Irvine in 2006, a married couple with five children admitted to keeping a 12-year-old girl as a house servant and slave.
The couple came from Egypt, where such arrangements are not unusual.
Culture clashes make human trafficking tough to spot, Tran said.
"It’s actually your everyday businesspeople trying to make a buck," she said.
Whether they are pimps or slave traders, human traffickers use coersion tactics to keep their victims from running away, Tran said. For instance, they might charge victims for transportation, food and clothing. Many keep their victims' identification.
"[The victims] know that they don’t have families, they don’t have identifications, and if they get killed off, nobody’s coming to look for them," Tran said.
State law limits fines for child human trafficking to $100,000. One group wants to stop that with a new proposition for the November ballot. The law would raise the maximum fine to $1.5 million.