Your opinion on the legality or common-ness of dumpster diving for boxes? (recycle dumpsters only)?

Legally you are not allowed to grab any trash or waste whether it be in the garbage dumpster or recycling bin. This is because of the liability for both the company where the container is on and the actual dumpster company. Although I doubt you would get in any kind of police trouble there is still the possibility of it. Ethically I see nothing wrong in reusing items which are doomed to be thrown out. You are not taking anything from the recycling companies and hopefully once you are done with the boxes you will recycle them. I see you as sort of delaying the delivery of the cardboard boxes to the recycling facility. Next time you see some potential for valuables in a trash can go for it, you will come across valuable items others are too scared to search for. Good luck in your dumpster diving!