If possible, the Aztecs were even more disgusting than we've been led to believe. Their priests had cloaks of human skin, blood-smeared rooms, sprinkled blood on food like sauce, captured Spanish (after they were sacrificed) would have their faces flayed off to make masks (leaving the beards intact); they also chopped the heads off any horses that they killed or captured for display. Displaying the severed heads of captured Spanish also disheartened many of the Indian allies who were with Cortes.
It's not PC to say so nowadays, but even the brutality and enslavement of the Spanish conquistadors was a definite improvement over the bloody rule by sacrificial terror of the Aztecs.
Historical Review: Megadrought And Megadeath In 16th Century Mexico (Hemorrhagic Fever)
"The epidemic of cocoliztli from 1545 to 1548 killed an estimated 5 million to 15 million people, or up to 80% of the native population of Mexico (Figure 1). In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death of bubonic plague, which killed approximately 25 million in western Europe from 1347 to 1351 or about 50% of the regional population."
"The cocoliztli epidemic from 1576 to 1578 cocoliztli epidemic killed an additional 2 to 2.5 million people, or about 50% of the remaining native population."