If you've ever smelled burning hair...
If you've ever smelled an outhouse...
Forget all of those smells, Sanctuary must be about 100 times worse smelling.
Dead, rotting people and animals everywhere.
We run around smashing, burning, melting, exploding, hacking and slashing demons, living dead and all manner of creatures.
Nobody cleans up anything. New Tristram opens to us with piles of bodies to be burned! Outside of Caldeum, there are no sewer systems. The Heroes never bathe despite being showered in gore and adventuring through the sewer in Caldeum and running into the depths of hell.
I'd rate Sanctuary an 11/10 for overall stink.
Probably one of the worst smelling fantasy worlds ever featured in a game!