Haha, I remember flying from Narita Airport to Bangkok after a little while in Japan and noticed the shit piled up everywhere. You get used to the unbelievably clean streets in Japan and really notice it when you go anywhere else.
I guess Korea will help segway you back to the decay of western society, I sure you'll notice the piles of crap everywhere when you get back Stateside dude.
Have a great flight buddy 😉