Debt collection agencies have not legal right/power to collect debts under the FDCPA. All someone has to do (if they are savvy enough to know this) is send you a cease and desist. Virtually every debt collection agency out there knows this and simply ignores the c&D until the victim, er, target gets a lawyer. But in doing so, they incur statutory fines of $1,000 per incident in many cases.

Are you simply going after the people who don't know they don't owe you money because they don't have a contractual relationship with you?