Zombies were extremely sensitive to the scents emitted by living creatures, except for those that had evolved to Level 3 or above, whose skin had evolved to be intact. If they were clean, their bodies would not retain any odd smell.
However, zombies generally carried an extremely strong stench of rotting flesh, particularly the ordinary zombies. Since the Apocalypse, not a single piece of intact flesh remained on their bodies, only nauseating pus-filled blood within their shells.
And this pus-filled blood was the raw material used to create "Sorrow Liquid." By allowing the pus-filled blood to ferment naturally over time, the anti-life substances within reacted chemically, turning it into a black, viscous liquid. This liquid was commonly used as Sorrow Liquid.
It had the power to cause a stench so potent it could kill. The overwhelming odor was hailed as an excellent item for impeding the sense of smell of zombies!
