There's a.difference between a dumpster for trash and a roll off headed for the scrap yard. To me picking thru trash for aluminum cans or whatever, is kosher morally, as well as legally in the great state of kansas. And if. There's any hint oof doubt in my mind I'd ask someone or leave iT if no ones round.
Kinda funny 5 years ago nobody cared if you dumpster dived, now that everyone thinks pop cans and like are worth gold its a problem. Use to knock on doors to ask before picking up curbside appliances and they'd have me clean out the garage while I was there and give me gas money to boot, now same people act like your there to rob them.