Who is buying all this stuff?

When I am in the middle of an expansion and have two or more auctioneers posting hundreds of auctions daily, I ask myself who is buying all this stuff?  Now that I am at the end of an expansion and my normal sales have slowed dramatically, but my transmogrification sales have taken off, I still wonder who is buying all this stuff?  
With transmogrification I have been starting to get an understanding of who my customers are.  I typically get an in game mail every other week from someone making an offer on an item I have in the Auction House or asking where I farmed up an item.  I have also had one in game mail thanking me and letting me know he had purchased my item.  
The other telling item about the transmogrification market is you often see characters standing around in Orgrimmar sporting looks that may have very well come from your stock.  While there is no real way to find out, I often imagine that most of the characters wearing plate-kinis on my servers are doing so because I sold it to them.