Yeah, that's pretty much how it is here. That's why I love when I get the chance to see a train pass by. There's always interesting graffiti art on the boxcars. I'd like to start photographing them sometime.
Some pics a friend takes related to your topic, where I live there's a lot of this stuff, sometime's its just trash, as you mention it, but if you walk around enough, you can find some pretty cool stuff.
This is were he posts his stuff, too bad it's insta but they're worth taking a look at.https://www.instagram.com/circuitoescritores/
I looked all around, only some better looking tags in one place
might try to do something myself, thinking of any ideas for that