Dumb retard detected>The slum cities
Their cities were famously clean, swept and washed by public workers, disposing garbage could get you enslaved etc.>the corn crop was failing due to smut.
Corn smut is totally normal and its also a food.>Remember that the Aztecs were on the verge of collapse
Quite farm from it, the spainards were just really good at staging an uprising and then playing out the independent cities, tribes etc. against eachother. They could do this because they were sitting pretty in their base in Cuba, completely beyond the reach of locals and able to intervene and resupply along the coast as they saw fit, not to mention having an entire kingdom back at home to draw recruits from.