Western men who visit red-light districts in poor countries often find themselves surrounded by coquettish teenage girls laughingly tugging them toward the brothels. The men assume that the girls are there voluntarily, and in some cases they are right.

But anyone inclined to take the girls’ smiles at face value should talk to Sina Vann, who was once one of those smiling girls.

Sina is Vietnamese but was kidnapped at the age of 13 and taken to Cambodia, where she was drugged. She said she woke up naked and bloody on a bed with a white man — she doesn’t know his nationality — who had purchased her virginity.

“My first phrase in Khmer,” the Cambodian language, “was, ‘I want to sleep with you,’ ” she said. “My first phrase in English was” — well, it’s unprintable.

Shocks fit well into the brothel business model because they cause agonizing pain and terrify the girls without damaging their looks or undermining their market value.