(the link again in case the clickable title doesn’t work on all instances: https://sketchtoy.com)
Have you ever tried to explain something over the internet that doesn’t translate well into words (like a specific route on a map, the layout of a building etc.) and you also can’t find a good picture on the internet showing what exactly you mean? Then just use that site to doodle a sketch. It is free of charge, doesn’t require a registration/verification/whatever or extra software, and the sketches seem to stay online forever.
I have an online roleplaying group that relies solely on chat / texts and this site has helped me numerous times to demonstrate the layout of a tavern, camp or dungeon, to show what in-game items look like and/or how big they are, and to add easy-to-understand visuals to in-game puzzles that would otherwise be hard to describe verbally.
Isn’t this why dumpster diving is illegal in many places?
As far as I know that is usually mostly a liability problem. Scavenging can be dangerous in the activity itself, and you don’t know “why” someone chose to throw away that “perfectly useable” thing. Maybe you get lucky and the reason was dumb, but there could be a very good reason. Either way the waste management company tells you not to, so when you get hurt or sick from doing it, it’s on you.