[jorleif]

While this is true, I would argue that there is a social expectation that an IMDB review is written by someone who has seen the movie. Especially, it is expected to be true on average with the usual "few bad apples" thrown in the mix. In this case, this expectation does not hold, and in this sense these reviews are truly anomalous (they are produced by a different process than the other ones). From the perspective of the expected usage of the reviews this anomaly is indeed possible to see as an error, rather than just slightly different behavior.