But they don't work. So many products and services are not useful. Simply not useful. On Twitter, I've started blocking every useless advertiser that decides to show me an ad... and I'm left with EXAAIR, who I'm sure is glad to target a computer software researcher with their compressed air-powered tools. There is simply too much advertising and too little space. How many advertisements, reasonably, can be sent to a person for things they legitimately want? Does that at all track with what they would see on the unfiltered web?