Dude, you're really getting annoying, you know that? You'd probably go postal if you saw the floor after a rock concert. Some guy getting $6 an hour is unfased by it. He and a buddy are cleaning out an entire screen in a fraction of the time it took to actually make the "mess." If, as you guys are saying, it takes not an iota of effort to clean up after yourself, it must not be much harder for someone for whom it's in their job description and has become routine.
It's not like I'm going to buy a blue XXL slushie just to dump all of it on the main front aisle next time I see this movie- I just think that, like maids make beds and replace the towels, and busboys clean up sit-down restaurant tables and wash dishes, and ballpark janitors sweep and pick up after 35,000 drunk people, the movie theater owners are unfased spending a few dollars to employ a couple kids to do what, as you or others have said requires not a single iota of effort anyway.
Then your theater needs to hire/fire their janitors who can't do their job. Theaters get $8 per person plus concession profits, and it should only take 3-4 seconds per used seat for an employee to clean up afterwards. That's about the same time it takes for you to get your ticket stub ripped.