In freighters, the bilges give incredible surprises.
The most amazing experience I recall, started when passing the gate to berth at Seaforth Terminal in L'pool. It was there where the Customs search gang boarded and started to comb the vessel up and down in any imaginable way; even the fridge in the Officers mess!!
The engine's bilges, no matter how clean they were, produced even funny results, exhuming absurd things surely hidden there (with smuggling purposes) by previous crews from many years before. Even now, I cannot explain why, all what they collected, ended in the Radio Officer's cabin which was up there at the bridge level. The collection of things was surreal, with wine bottles and cigarettes of brands unknown even to us. The most outstanding thing, left in a prominent central place, so it was staring at you when you entered the room, was an inflatable doll.
I could tell about Libya and Iran as well but I believe that nowadays that folklore is over in most parts of the world.