The Pardoner reveals his trade secrets by describing them to the other pilgrims in the prologue to his tale. He takes them step-by-step through the fraudulent sermon he gives as he travels to different churches.
He first tells the worshippers that a love of money is the root of all evil. He follows that by establishing his authority as a cleric by showing letters from bishops and Papal bulls (written documents) that approve his work.
He then shows the worshippers a false relic, which he keeps in a brass box. It is a sheep bone, but the audience assumes it is a bone from a saint's body. The pardoner then tells his listeners that if they put the bone in their well, they can use the well water to cure their animals of diseases. Also, if a person drinks this well water, it will cause their animals to multiply and cure the drinker of jealousy.
Having gone over the benefits of the false relic, the pardoner then uses manipulation, saying that only the worst sinners will not want to come forward to be forgiven of their sins. This assures him that everyone will step to the altar to receive a blessing and a pardon in return for a cash payment.
The pardoner then brags openly to the other pilgrims about how his lies are believed by stupid people. The pardoner shows himself to be a hardened person who is proud of his con artistry. He wants his listeners to know how good he is at what he does and reveals no shame at all about defrauding innocent people by abusing their religious faith.