[masraum]

I think I've heard that once you "buy" a unit, you've usually got until the end of the day to have it completely empty. That sounds like a huge pain in the rear. I suspect like a lot of things, you'd need a big trailer, and then you'd have to sift through a ton (literally) of junk to find the occasional "needle" that wasn't junk. Then you've got to have a way to dump the junk after you've sifted. I think that's often also not free. If you include the price of the unit and then your time, I suspect you don't break even.

But I've never done it, so maybe I'm wrong.

My guess is that some/a few folks make a little money at it, and a bunch of folks lose money as they are probably gamblers looking for the next big score.