Lots of scientists don't read what they cite

Simkin and Roychowdhury conclude, using some elegant math, that only about 20 percent of scientists who cite an article have actually read that paper. This means that four out of five scientists never take the time to track down a publication they intend to use to buttress their arguments. 

Samuel Arbesman, The Half-Life of Facts: Why Everything We Know Has an Expiration Date (New York: Current, Penguin USA, 2012), ch. 5 (citing M. V. Simkin & V. P. Roychowdhury, "Stochastic Modeling of Citation Slips," Scientometrics, vol. 62, pp. 367-84 (2005))