In the early Ebay days (late 90's) they had a policy against selling Promo which I have to assume that was initiated by the major labels.
In '87-'88 I discovered the dumpster at the local WEA warehouse. All the promos that they sent out that were returned went into the dumpster and my brother and I would hit it twice a week and literally hauled off tens of thousands of promo CD's, LP's and 12" over a 2 year period. We sold them to all the local stores and word got back to us that WEA suspected that an employee was stealing this stuff because there were more promos showing up in Dallas than they sent to the entire state of Texas. At the end of '88 they moved the warehouse to a new location and when they did they filled the dumpster to the brim every day for 2 weeks with posters, promo items, etc., etc. We hauled out stuff like Metallica glow in the dark vinly 12", REM interview discs and 200 copies of a Prince poster that had been recalled due to Prince not liking it. My brother put himself through college with what we found in those dumpsters.
At the new location they wised up and put the dumpster in a locked, enclosed fence.