These victims are usually promised very good jobs, better working condition with a very good pay. The offers are often very enticing and it is very difficult for anyone who is swimming in poverty to say NO to such offer. It is quite unfortunate that they don't get to meet what they bargained for and they end up doing jobs and working for people they ordinarily wouldn't want to do or work for.
These victims will most likely be immigrants as well, coming from third world countries where they have lost all hope of a good life, such people are quick to jump on employement offers in another country and they do not hesitate to sell everything they have back at home, in order to fund the trip, but they do not know that they are being shipped into forced labor for criminal organizations. It is up to the authorities to ensure that we see less of these things and also up to people to verify every nuance before taking up any job.