I've heard most are scams..

I think you heard right. Most , if not all, are scams. My son did this work when visiting his Dad in Texas one summer. I didn't know about it until he called me in Calif. to tell me he had no money to get a motel room or even eat. I can't remember all the details because it was years ago, but I do remember he was upset and near tears. The supervisor in charge wasn't paying them what was promised and they were on their own. It seemed they traveled from city to city in a van and the workers walked neighborhoods trying to get subscriptions. I think they had a quota to fill each day to get paid. He was only 16 or 17 and had never really worked any job. I wish I could remember more. Anyway, I wired him money the next day to get him back to California. It didn't seem in any way beneficial to those walking around trying to make sales.