Tlazolteotl

Here's my take on Tlazolteotl, the Aztec goddess of filth, purification, steam baths, lust, midwives, and the "patron saint" of adulterers. Her name can be translated as "deity of dirt", but she is also known as Tlahelcuani, "she who eats dirt" (or "she who feeds on sin"), or Tlazolmiquiztli, "death from lust". Her Mayan equivalent is called Ixcuinan, a deity divided into four goddesses associated with lust, differing by their ages ; apart from that, there are no notable differences with the more famous Aztec version.

Tlazolteotl was an ambiguous, elusive goddess who incited mortals to sexual vice (notably adultery), while inflicting venereal diseases on those who indulged in forbidden loves, according to "The Daily Life of the Aztecs" by Jacques Soustelle. But at the same time, the moral and physical impurities caused by these vices could be cured by purification rites or steam baths, over which the goddess also presided.
It is said that those who wished to obtain the purification of Tlazolteotl could go see a Tlahpouhqui priest who, after consulting the ritual calendar of 260 days, determined the appropriate day and time for the ritual. Scarifications and fasting punctuated the expectation of judgment. When the time came, the priest meted out justice, and ordered the penitent to go through singing and/or dancing rites, or to bring various offerings, depending on the gravity of the sin. All this being granted only once in a lifetime, sinners generally confessed at an advanced age.
That said, these details about confession to the priest having been reported by the Franciscan missionary Bernardino de Sahagún in the 16th century, it is reasonable to suppose that the latter tinged the Aztec customs with Christianity in his Florentine Codex.
But Tlazolteotl, as her other name Tlahelcuani underlines, is indeed a goddess who, by feeding on the sins of mortals (symbolized by dirt, or... excrement, as it was theorized by Cecelia F. Klein), purifies them. She also has a big dark stain around her mouth on most of her depictions.

Human sacrifices are said to have been offered to her, where the skin of the sacrificed was removed and worn temporarily by a priest, similar to the sacrifices dedicated to Xipe Totec, or wrapped around an effigy of the goddess. The sacrificed were sometimes young men, sometimes prostitutes, called auhianime. With Piltzintecuhtli, a god of the rising sun, medicine and hallucinogenic plants, she had a son, Centeotl, the god of corn.
Tlazolteotl was perceived by the Toltecs as the incarnation of the unconscious and/or subconscious forces of humans, and of the basic instincts which frighten us, of what Freud called the "id", in short.
Finally, she was one of the deities that the Aztecs celebrated during the month of Ochpanitzli, which extended from September 2 to 21 of our calendar. During these festivities, great ritual cleanings and repairs took place, which corresponded to the purifying aspect of the goddess, who was also sometimes represented with a broom.