Only a small number of the workers interviewed by The Times said they had ever seen an investigator, from any government agency, at their salon.

Among the Labor Department’s 115 investigators statewide — 56 are based in New York City — 18 speak Spanish and 8 speak Chinese, essential tools for questioning immigrant workers to uncover whether they are being exploited. But just two speak Korean, according to the department. Department officials say all of their inspectors have access to interpreting services.

When investigators try to interview them, manicurists are frequently reluctant to cooperate, more so than in any other industry, according to a Labor Department official involved who spoke on the condition of anonymity because the official was not permitted to talk with reporters. “It’s really the only industry we see that in,” the person said, explaining that it most likely indicated just how widespread exploitation is in nail salons. “They are totally running scared in this industry.”

Manicurists are also required to be licensed, but this is another area where enforcement is lax. There are nearly 30,000 licensed nail technicians in the state, according to the New York Department of State, but numerous manicurists work without licenses. Licenses are frequently fabricated, bought and sold.

Manicurists say that even when government agencies do check on their employers, evasion is easy.

Lili, a manicurist from Ecuador who is picked up every morning in Flushing near Ms. Ren, laughs when she recalls the time state inspectors visited the Westchester County salon where she works. Spotting them, her boss barked for all the unlicensed workers — there were 10 — to hustle out the back door.

“So we left, we got in the car, and we took a spin around the neighborhood,” said Lili, who declined to give her surname because she is in this country illegally. “Twenty, 30 minutes later we returned. After they’d gone. We put our uniforms back on and we returned to work.”

No Refunds

This past fall, Ms. Ren’s parents arrived from China. Work had dried up for her mother, an insurance saleswoman, and father, a sometime chef, and they missed their only child. The visitors stuffed the one-bedroom with a total of eight bodies before Ms. Ren, her mother and her father had to move out. The manicurist packed up her pet fish, and the family installed itself a few blocks down Union Street in a dank basement apartment, where for $830 a month the three share one bedroom.