I was looking for some explanation of the loot spawn mechanics in DayZ and I got here.
I'm still looking for a definitive answer, but my observations suggest Mr Smooth is wrong in many aspects.
I described some of my observations below. but be aware all can change in new versions.
For now (version 188.8.131.52 and my current experience), my hypothesis is, that the mechanism which determines what loot spawns (if any) is triggered when a player approaches the location and the distance gets below some threshold. I suspect that this mechanism could be triggered by purposely entering and leaving the zone. I don't know what the distance is and if it's the same for all types of buildings or spawn spots. Also, I don't know if entering the zone triggers one time roll only or if it starts some process of many rolls over time. In the first case it should be possible to generate a new loot by entering and leaving the zone. Maybe even a few steps back and forth would do the trick, but one would have to know the exact distance. In the second case, there is no need to move. One just has to get within range and wait. Getting too close stops the process (assuming there is such process)
Loot definitely doesn't spawn with time when there are no players near. I saw too many almost completely empty fire stations and other buildings, when I rushed into them from far away. There was plenty of time for loot to spawn before I had come, but it didn't. Moving in the vicinity of the spots, changing the distance leads to more loot appearing over time.
It is also not true, that there can't be any players near the loot spawn spot. I have experienced loot suddenly appearing next to me in the past. But I think other players moving nearby are necessary for that.
Of course loot can't spawn in an occupied spot, but it is not necessary to take the garbage 100 meters away. I managed to get new loot in the barrack at the airfield, after dumping the garbage at the entrance, just outside the door.
I think crash sites are a different story. I don’t believe loot spawns near them after the initial one gets picked up. But they are way too rare and dangerous for me to gather enough experience and observe the behavior.