The best bill collectors use manual or automated systems to keep track of debtors, and when they contact a debtor, they have all of the facts in front of them. It is very common for a debtor to say `I just sent you a check a few weeks ago', or `I paid that off last month', or some such thing. A good bill collector should know how long a check takes to arrive in the mail and should know authoritatively how much of the debt was paid last month. In the face of detailed facts, most debtors recognize the truth, come to their senses, and pay their bills.
/'s tiny experts have great memories. They remember everything that you tell them about the debtor they track, everything they do automatically, and everything you tell them about each case. They remember the date each thing happened, the order in which things happened, and can recall all the details on a moment's notice. When you are on the phone with a debtor, summaries of the debtor's case and history are provided, including tendencies toward lying, being late, and being abusive.