Dodgy-looking guy wanders up the gangplank of a ship in dock, and asks for the captain.
Hello, he says, I'm looking for a job working on a ship.
First mate takes the captain to one side, and says:
Dunno, captain, he's a shifty-looking fella, his eyes are too close together and it wouldn't surprise me if he's running away from something.
Captain thinks about it for a bit, and decides to give the applicant a chance.
Three months later, on the high seas, a huge wave arrives unexpectedly and washes the new bloke over the side as he's mopping the deck.
Mate rushes up to the bridge, and says:
I told you he was trouble, that new bloke's just f*cked off with your mop.