Join the crowd. I lost three contacts within a week due to people going to haul their own stuff to the scrap yard. Another was to a guy who claimed he was my son and running my route cause I was in the hospital for shoulder surgery.

But - if you get up something like a Code of Ethics, that won't solve anything. The only people abiding by it will be those who sign it - it won't stop others from anything. So, you'd want a law that people could only sell scrap to "licensed" dealers. Or scrap yards could only buy from registered/licensed dealers? Not realistic.