I've always felt that caterers weren't actually people, or at least not human beings. People do some pretty bad things to one another, granted, but the obliviousness that caterers continue to bring to their work after the many gigs that most of them have done is astounding.
I worked last night at the American Museum of Natural History. There's a loading dock with a driveway on Columbus there. The truck comes down the driveway and into a courtyard, then stops outside some double doors and the crew pushes things down a ramp, immediately up another, and into a paved hallway. From there, depending on the room, we have a lot of different ways to go. Everyone takes the downward ramp at a run, in hopes of using the inertia created to get the load a lot of the way up the following ramp. Last night, the caterers dumped out their desserts at the bottom of the two ramps. Chocolate mousse, served in what looked like they were once Martini glasses. I discovered this when it caused me to roll the cart I was pushing, dumping many medium-sized boxes of lighting equipment into the chocolate swamp at the bottom. Now, whoever is in the shop today is sorting and returning equipment that's oddly sticky and smells like chocolate.
The thing is that this is not an isolated incident. Caterers have a talent for finding a bottleneck in the path that everyone's equipment has to take in and out of a venue and then dumping some kind of waste there. Ice is a definite favorite. This leads me to conclude that either they're evil or they're operating at some subhuman level in which experience and awareness of their environment do not play a role in their decision-making process.