@Euroxati - Yes, as a matter of fact, I do. I'll even admit that I've been guilty of doing this. For example, there have been times where I'm at the movie theater, and when the show ends, instead of throwing my popcorn away, I leave it for the janitors to take care of.
On another note, I've seen others do this myself. If someone spills or drops something on the floor, they might be a bit hesitant to pick it up, because it's the janitor's "job". While it may not be one of the best positions, I still feel that it's underappreciated. Sure, it's a dirty job, but someone has to do it.