In our area, the book scanners have been out full force for a few years.
They take the media area at yard sales (DVD's, CD's, Books) and totally block it off from everyone else until they are done scanning each and every item. And if you try to get an item to buy out of "their" area you get yelled at by them. As if they are buying the entire collection.
They are annoying.
DH has a book scanner on his cell phone. We never use it.