Perhaps the best explanation of why this might be so was offered in 1963. In “Formal Theories of Mass Behaviour”, William McPhee noted that a disproportionate share of the audience for a hit was made up of people who consumed few products of that type. (Many other studies have since reached the same conclusion.) A lot of the people who read a bestselling novel, for example, do not read much other fiction. By contrast, the audience for an obscure novel is largely composed of people who read a lot. That means the least popular books are judged by people who have the highest standards, while the most popular are judged by people who literally do not know any better. An American who read just one book this year was disproportionately likely to have read “The Lost Symbol”, by Dan Brown. He almost certainly liked it.
Sounds to me like people should read more. If they enjoy crappy books, imagine if they were to read something good.