Click Farms
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Never heard of these before.
https://www.cnn.com/style/vietnam-farms-jack-latham-beggars-honey/index.html
From Wikipedia
A click farm is a form of click fraud where a large group of low-paid workers are hired to click on links or buttons for the click fraudster (click farm master or click farmer). The workers click the links, surf the target website for a period of time, and possibly sign up for newsletters prior to clicking another link. For many of these workers, clicking on enough ads per day may increase their revenue substantially and may also be an alternative to other types of work. It is extremely difficult for an automated filter to detect this simulated traffic as fake because the visitor behavior appears exactly the same as that of an actual legitimate visitor.[1]
