What qualities Chaucer to place the pardoner at the very bottom of the social world?

Chaucer describes the Pardoner as a gelyng..... a neutered horse (possibly a female). He travels the countryside selling relics, many of which are not authentic, and pardons that entitle their purchasers to forgiveness. In essence, the Pardoner, is a cheat.... a petty criminal, who berates the citizenry for their sins, sells them pig bones, and cheats them out of their money..... all for financial gain.