Roof Trash

I am very intrigued by the use of the roof next door as a trash receptacle. I noticed several random discarded items appearing on the roof starting shortly after I moved in. First, I think, was the bag of oranges, which is now decayed passed recognition, followed by the rug, window screen, and dead potted plant. Today, when I looked out of my window I saw a new even more impressive addition, an actual full bag of garbage. The thing that really intrigues me about these occurrences is how and why? One possibility could be that someone is throwing the items from my building which is taller and I could easily open my window and toss something over. But I ruled out this explanation because the items are on the far side of the roof, not the side closest to us. Also, it would be impressive to throw a plant and have it land right side up with all the soil where it should be. The other option would be that someone on the top floor of the roof trash building is swinging it up on the roof, which would be a lot more difficult, and the plant still doesn't make sense. The third option is that someone is walking up onto the roof with trash and leaving it there. This is the most likely scenario. This is where I get to the why. Why on earth would someone do this? If someone is too lazy to take out the trash, it takes probably just as much energy, if not more, to walk the trash up stairs to the roof instead of downstairs to the actual trash receptacles. Maybe they are saving it for later, which would be very strange indeed. It is beyond me.