Plymouth Crown Court heard the victims, from the Czech Republic, slept in garages while the defendants pocketed their wages and benefits.
The victims were described as "malnourished and unkempt".
Five defendants deny conspiracy to traffic for the purpose of exploitation.
The defendants are:
Malcolm Galloway, prosecuting, said "at least three of the alleged victims were living in a garage" and Petr Tancos had "encouraged his children to throw stones at them", the court heard.
The court was also told that when Ruzena Tancosova was arrested last September after a police raid, she asked how long she would be in prison.
Intelligence officer Det Con Neil Albrechtsen told the court he stumbled across information in 2012 which led him to Josef Bukovinsky, the first immigrant interviewed by police.
He said while checking records he realised Bukovinsky and Josef Stepan, also Czech, had applied to the United Kingdom Border Agency for repatriation.
The trial continues.
Vulnerable eastern Europeans trafficked to Plymouth were ordered to cut grass with a kitchen knife and clean a car with a rag, a court has heard.