About eight years ago, my team and I at Procter & Gamble had the opportunity to take one of the largest media buy and deploy companies to task - we had been paying them, in seven figures, for bot clicks on online advertisements. The worse part of it was, they had no clue themselves.
This occurred when we were building and rolling out the women's word-of-mouth marketing brand VocalPoint, see the site here. Leveraging my personal global network across ISPs and internet based companies, we developed the hypothesis of the bot clicks, and then we proved it through data analysis.
It is fascinating to see that today it remains just as bad.
"On July 30th Limited Run, a New York platform for the online shops of record labels, artists and designers, said it would delete its Facebook page. It estimated that 80% of clicks came from “bots”—computers rather than people, but triggering payments to Facebook all the same."
See The Economist's article "Facebook: Work in Progress" here.