Something that always bothered me when i was younger was the statement that was constantly quoted as fact; "We currently only use less than 1% of our brain." Or less or 10% or some other nonsense. I was and still am a reader of pretty much anything i can afford to get my hands on and in all the articles and books i had read on the brain had never come across proof of that little tidbit.
Later when i was "in the nest" my morning seat assignment was next to a member of the writing commitee. One day when we had gotten to know each other i asked him if he could look up the reference for that for me. A month or so later he handed me a slip of paper with the reference. You should have seen the guilty look in his eye. I slipped it into my pocket without looking and left for my work assignment. It was from an article by Carl Sagan. I figured ok, i can respect carl sagan but then i looked up the article and found out they he was just speculating. His words were, "Some scientists believe that we may etc..." Drove me nuts that this little piece of wittness folklore had been used as basis for fact for so long. Oh well...