Easy. We live in a world in which 2 year old children get prep courses so they can score high on the nursery school entrance exam. That kind of environment is perfect for almost any myth about testing to take hold.Where do rumors like this come from..........(!)?
So far no examiner has ever mentioned my knowledge test scores. The examiners I know personally don't mention it either. Some will understandably (they are human beings after all) have some expectations with a very high score of a barely passing one, but they tend to go by the wayside very quickly, usually in the first few minutes of the oral.