Spoilage couldn't be global because at some point the player would only find spoiled food.
Not necesarily ...
I mean *we* dont know where boards of locations are, since the map is everything just mashed together ... but Larian should ... so, purely teoreticaly ... they *could* tie rotting of food to certain locations.
Also, not every food in the world should spoil ... i mean if you take basicaly any food you find inside the groove, it would be logical to presume they get rid of bad one, and gathered something else somehow.

It would look kinda off, if that Tiefling grandma who is cooking that soup would have rotten meat on those hooks in her little shop.

And finaly there is still that suggestion with processed food, that would not spoil.
