Even the oppressed oppress others; the victimized and excluded exclude others. There is always someone else whose exclusion will make us feel better. Hated but also hating. One could imagine that the inner life of this small group of lepers, rather than their leprosy being the great equalizer of former animosities, merely repeated the usual perversions of exclusion. Hated but still hating.
The Samaritan in this reading is unclean for two reasons: ethnicity and leprosy. When he is made whole, is it only his leprosy of which he is healed? No, surely not just his leprosy is gone but also his conformity to the system that makes 'lepers' and 'Samaritans'. The Samaritan comes back to Jesus who is the source of his physical healing and his wholeness as a full human being, united through faith in Jesus with all those entering this new humanity.
Contrast the behaviour of the nine Jews with the Samaritan. They go to be certified clean by the priest; that is, returning to the system of exclusion through an officer of the system (the priest). From the point of view of the system (of ordinary religion) the nine Jewish lepers only required a single cleansing. They were part of the system before they contracted leprosy, and wanted to return to live within the system's confines. It is the Samaritan (he was never part of the system as a Samaritan) who sees that Jesus, by healing him equally with the nine Jews, also offered him liberation from the system itself.
One could be forgiven for thinking that the Samaritan, if he was meant to report to a Jewish or Samaritan priest, didn't bother. He had escaped the boundaries he formerly accepted forced on all of us by the universal human propensity to create boundaries of ex/inclusion. He would still have been hated by many, but no longer hating. His eyes had been opened.