God forbid someone picks their trash up, much less actually takes their trash bag out.
There's a funny moment I recall on the topic of leaving trash behind.
I was flying with the then-pro-standards chairman, back in 2009. Great guy, very funny...and physically enormous stature.
I walked down the jetway to an empty jet and I got my stuff put up front first. I noticed there was a very large pile of newspaper on my side, but neatly left there as it was apparently that day's copy of whatever it was.
I didn't want it, but I thought el capitan might so I took it and placed it over on his side. I went outside to do the walkaround just as he was making his way down the jetway.
I came back up the jetbridge stairs a few minutes later from outside to see the same newspaper tossed wantonly all over the place in different sections in the area where the cleaners had trash bags in the jetway.
I thought, jeez, I guess [captain] already read the paper today 'cause he sure doesn't appear to want this one.
Back in the cockpit, I said nothing of it and we did our usual duties.
After the flight, during the next turn, [captain] mentions to me that he's a little miffed at the captain that brought the jet in for our previous flight. He told me he'd just gone into the system and looked up who it was, and he knew the guy, and said of him, he really ought to know better than to leave his newspaper tossed all over my side of the cockpit. He then added that he left the guy a voicemail stating as much -- and as we were on day four of an early morning type trip if I recall, and pretty much ready to be done with it, the voicemail turned into a bit of an aural nastygram.
I had to tell him.
We had enough hours in the cockpit together previously that I knew he wouldn't be miffed at me but instead would probably find the whole thing funny. And that's just how it went.
I said to him, I think you may get a confused call back from that other guy . . . because I put the newspaper on your side after I unpacked since I didn't want it. While I was outside, it must have fallen off the side console and then gotten blown by the [insane hurricane] ventilation system in all directions. When I came back in and saw you'd dumped the whole thing on the jetway floor, I thought you just really did not want it.
We laughed at the scenario and he said when he entered the cockpit it looked like the previous crew had just picked up the full newspaper by a corner and shook it out all over his side of the cockpit. He messaged the guy back and said disregard.
Ever since then I leave nothing behind even if I think the next crew will want it. Never know when some eyeball vent in the corner is going to turn it into something completely different.