Looting through walls is a minor issue, as both you and the item have to be very close to the wall in order for it to work, but for ceilings/floors it's a much bigger issue as it seems to always work regardless of distance, essentially letting you loot the roof of a building from the ground floor, providing you are standing directly beneath the items.
From what I have tested, this works on all servers, all buildings and with every item in the game.