I've long been a student of a phenomenon I call "manufactured credibility," in which the Internet makes it easy to fake popularity and approval for everything from books and consumer products to politicians. One of my early writings on the subject was inspired by the saga of a guy who made good money running a business that supplied planted reviews to sites like Amazon.com. You paid a fee to his fairly large and sophisticated operation, and his people would flood the big consumer websites with highly convincing, authentic-sounding positive reviews for your book.
What intrigues me about manufactured credibility is how easy it is. I'm not talking about informal penny-ante stuff, like your friends jumping on YouTube to write enthusiastic recommendations for your latest video. I mean industrial-scale efforts to manipulate opinion by using the Internet as a tool to artificially inflate popularity. There's not much cost involved, and it's very difficult to see through the illusion. And it's an interesting comment on mass psychology that people are powerfully swayed by the sense that a large number of "regular folks" approve of something. At the very least, they find illusory popularity intriguing, and want to know what all the fuss is about.