It sounds like a variant on the unemployed/homeless useless dusters scheme, on which there have been numerous threads. Someone who knew someone who'd actually sold dusters for such a scheme said they were paid a pittance for doing so.
No, we haven't had prisoners round here yet.
I used to buy things I didn't need, until I had three such people call in a week and I noticed my cupboard was full of useless cleaning items. I have since come to the conclusion that, if these people are genuine, they'll learn more about how to run a proper business if I give them some honest feedback (politely of course) about the quality of the products they sell. My doorbell's gone a bit quiet since... I wonder why.