Good points, I’ll look into the other studies at another time. I remember a german newspaper actually switching completely to non-targeted ads after their own experiment, but can’t find the source anymore. I’ll comment it here, if I find it again.
Thanks especially for your transparency on your Motivation and Disclaimer.
The problem of inflated ads is currently very real for bigger players, who rely on paid traffic—I’ve worked with a company which did buy large quantities. They were employing several employees to just check and negotiate with the ad-publishers each month about the fraud rates, because the performance (meaning the chosen method—i.e. CPM, CPC, CPL, CPA) were vastly different between the ad-publishers, and it didn’t make sense.
So there definetly was fraud involved, but it was extremely hard (and expensive) to weed fraudulent advertisers out.
Your scenario of an email newsletter is a special case, because it’s virtually impossible to introduce any form of client run code to check for fraud, and can only start your fraud detection after the traffic hit your website.