In the postal automation / postal automation arena the sequence numbers of automated postage vending machine receipts (and print to order stamps) have been used by collectors for years to determine the number of transactions at newly placed kiosks. Likewise, stamp journals publish the serial numbers of postage meter placements each month which permit determination of the relative numbers of units being placed by competing companies. A good understanding of a system often makes it possible to obtain unexpected insights into the competitive landscape.
Well, you are correct, this is really common. Dumpster diving is nothing new. According to a close source who I shared this article with... the source laughed out loud. The source stated that they fulfill the act of dumpster diving on their competition all the time. As a matter of fact, the source went on to say that they hire people to dress like they are homeless to help with the process. Facebook and the others are good, but why waste time with that when you can go for the real thing....dumpster diving.
The teacher who ran the electronics club that both Steve W. and Steve J. belonged to in high school routinely took the students for dumpster runs in the Valley to scavenge for scraped electronic parts. So it is indeed a time-honored tradition!