Hi Ad Fraud Researcher — Thanks for the note! My definition is more of bot=fraud and humans that are on pages that mimic user behavior as I mention above = fraud. All other are just low quality sites.
As for the buyers not choosing to buy, I completely agree. When I had discussions with a writer from a big media company last week, even he mentioned that when he would reach out to advertisers, they would just say if they do not want the inventory, they do not buy or will place a domain on a blacklist. That is where the onus is for less quality traffic.