I do comics lettering for many publishers, and I found myself doing a DC series for [to me] local writer Marv Wolfman, of whom many of you may know. He was having a BBQ at his home and was kind enough to invite me---this was yee-ears ago. Seems I was the first to arrive, so we talked in his office as we waited for others to arrive. He had a framed Superman Shuster page above his writing desk on the wall. I asked about it and he told me the story of how when he and Len Wein were fanboys, not yet pros, but kind-of industry insiders [1969 or so] he was in the DC offices soaking up the fanboy wonderfulness when someone came by with a cart of original art that was going to the furnace or the trash or something. They were essentially asked if they wanted any as a souvenir. Turns out Marv had the whole Superman story--he was able to pick out all the related pages from the pile. He [and I] wished that he could have taken the whole stack, but it was cumbersome at best. Not sure what Mr. Wein took, but I'm sure he didn't pass on the offer.
Another story I recall from, I think in Comics Interview magazine---it was an article/interview with Gil Kane, one'a my all-time top fave comics artists...he was relating a story where in the mid 60's, he'd drive into Manhattan [prob'ly from Connecticut or Long Island] to drop off pages. If it was snowing, he'd grab old pages from somewhere and toss them onto the floor of his car to keep the dirty snow from soiling the car's rug under his feet while driving. Even as he told the story [in the 80's, I think] he seemed to wince at the idea...but in the 60's the art was just a by-product of a job. The artist usually didn't want it back, and so the pages were thought of as worthless. It wasn't until the fan movement showed interest and when Comics were deemed a true American art form that the pages were then thought of as a commodity.