since you were clearily trying to make one of your passive agressive "points" about the dead 60s by implying a pile of used cd indicated that people thought they sucked and were selling them back.
a promo cd is one set out to any of a number of outlets to promote the product. (radio stations, djs, clubs, street teamers, magazines, record stores, independent record promoters) a promo can appear to be used since it's open but will usually take some sort of sticker indicates it's a promo, or a indent/hole in the case. as is the often case someone is trying to raise a little cash by selling thier promos. given the fact the cd just came out that pile of used cds is probably someone cashing in their promos.
could be that some radio station got a stack to give away and some intern decided to pocket the cash instead...