This is a must read for anyone who buy or is involved in buying advertising online. It is not sufficient to read a media agency's ad performance report. Go check out the sites your ads are on. Spend time in the ecosystems you advertise on, wether is social networks, mobile apps or other platforms. Develop analytical reflexes to grasp what ad fraud looks and feels like. Run tests with smaller budgets. Because according to this report, the state of ad fraud is not good.

State of Digital Ad Fraud Q2 2018 from Dr. Augustine Fou - Independent Ad Fraud Researcher