How does one shi'ite on the walls unless the turds are tbhrown there afyer the fact?
obviously.
I've read about the British being revolted by IRA prisoners who smeared filth on the walls of their cells. The IRA claimed that the British would not take the waste buckets from the cells and it was actually more liveable to spread it around. And since it was the prisoners who had to live there...
In this case, I'm betting on sheer nastiness. I'm not saying every ugly thing there happened was out of desperation.