Of course no one ever buys a new vacuum just to have "newer, better" and maybe snazzier then parks a still perfectly serviceable old mare in the closet because it's old and boring, or maybe not as ergonomically perfect as some newer thing. Or the owner simply does not know how to change filter materials and the machine finally loads up with dirt and starts blowing dirt out the back. Still a good machine but the owner(s) don't know how to take care of their belongings. Heck, I have to beg my fiancée to let me change the oil on her car, doesn't see the value in it.
As I am finding out there are an awful lot of good running vacuums being discarded. They are ugly and filthy, having been used and abused for a couple of decades, but despite the abuse still run fine.