Google is by far the most problematic. You are paying ridiculous amount of money for a click you don't even know came from a legitimate source. There are many

Google is by far the most problematic. You are paying ridiculous amount of money for a click you don't even know came from a legitimate source. There are many many botnets out there undetected running headless chromium browser instances that is indistinguishable from a real one. So if you can't tell and then you will never know if you are paying for legitimate prospects or not. However, advertising for established brands direct response isn't what they are going for rather brand awareness