Ancient Stench and Corpse Removal

My "research" into the stench of ancient cities has thrown some light on a couple of passages in Jewish literature that always puzzled me. The ancients seemed to take a remarkably laid-back attitude to corpse removal, as this quote from Suetonius shows:

During Vespasian's aedileship, the Emperor Caligula, furious because Vespasian had not kept the streets clean, as was his duty, ordered some soldiers to load him with mud; they obeyed by stuffing into the fold of his senatorial gown as much as it could hold ... Then a stray dog picked up a human hand at the crossroads, which it brought into the room where Vespasian was breakfasting and dropped it under the table. (HT: David Noy).

My guess is that the corpses that tended to accumulate in the open were those of foreign travelers, slaves, criminals, or other pariah groups. This explains, I think, why Tobit was able to keep pretty busy at his avocation of burying fellow Jews:

If I saw the dead body of any of my people thrown out behind the wall of Nineveh, I would bury it. (Tobit 1:17) [Tobias said]: “Look, father, one of our own people has been murdered and thrown into the market place, and now he lies there strangled.” (2:3)

And lastly, the Mishnah quotes a saying of Hillel (Pirke Aboth 2:7):

One time he saw a skull (or: head) floating on the waters, he said to it: Because you drowned others, they drowned you; in the end, those who drowned you will drown.

I always thought the occasion for this saying was strange; how likely was it that someone would see a human skull in the water? But now I can see that it would not have been that unusual.