Via @jpeterburger I found this paper by Ole Bjørn Rekdal on how urban legends in Academica exist and even grow. The abstract and start is really harsh:
Many of the messages presented in respectable scientific publications are, in fact, based on various forms of rumors. Some of these rumors appear so frequently, and in such complex, colorful, and entertaining ways that we can think of them as academic urban legends. The explanation for this phenomenon is usually that authors have lazily, sloppily, or fraudulently employed sources, and peer reviewers and editors have not discovered these weaknesses in the manuscripts during evaluation. To illustrate this phenomenon, I draw upon a remarkable case in which a decimal point error appears to have misled millions into believing that spinach is a good nutritional source of iron. Through this example, I demonstrate how an academic urban legend can be conceived and born, and can continue to grow and reproduce within academia and beyond.