This has pissed me off for years.
In the mod, you know exactly what building spawns what type of loot. Industrial building spawns industrial loot.
But in SA, it seems to work on a 'zonal' system. If say, a supermarket, is close to a police station, then the supermarket will spawn the same loot as you'd find in a police station.
If a small garage is close to a hospital, then expect medical clothing etc etc etc.

If ia player us looking for a certain type of loot, then it is imperative that there is a reliable way of finding it.