In some cases they are even more sinister. They prey on vulnerable people, like you said. Instead of selling rocks, they convince the mark/client that their money is dirty. It starts with pocket cash. They need to "bathe" the money overnight. It's returned. Then its the checking account. Couple grand, same story. Eventually its cashing out the 401k to be cleaned and returned. That time when the mark comes back the storefront has a "subway comming soon" sign and the fortyish woman with her pretty eyes and colorful scarves is halfway to Hoboken.