Think of the last long-haul flight you were on, transatlantic or otherwise. Walking through the business class cabin upon exiting the plane after landing, I've frequently marvelled at what a mess some people can make. Granted, the more the folks up in the pointy end are given to enjoy their in-flight experience vs. economy passengers, the more gets left in/around the seats and all over the floor. All that stuff is nicely and neatly packed in galley carts and bins to be loaded, but once unwrapped and consumed, will fill up a small dumpster.

Now scale that up to an entire 757.