"I don't write $GENRE books" - $GENRE authors with no respect for their audience
Roland bathes said that just because it comes from the horse's mouth doesn't mean that the horse is telling the truth. The horse may not even know what the truth is.
In his Nobel Prize acceptance speech, William Faulkner wrote that *The Sound and The Fury* was about hope and the indomitable nature of the human spirit. My high school English teacher was skeptical of Faulkner's claim, and I think a lot of other people are, too.
Well there's [Dan Brown-ing](http://tvtropes.org/pmwiki/pmwiki.php/Main/DanBrowned
) (warning: TVTropes link) but that isn't what you're getting at here. :P
I can't think of any examples from the author, but I've seen some from fans that make me sad. The one example I can remember right now is stories of people dismissing Diana Wynne Jones' books because her fans were really nasty about Harry Potter way back when. Which makes me very sad, because why can't they both be good? :/
I have noticed that authors who don't work or study in a certain field and then write a book in that field think they are writing something revolutionary. Yet, those of us in that field in some way have known whatever the book is about for years.
That... Kind of sounds like the sort of thing that a professor of literature (assuming that was his area) would say in order to justify all that wild speculating they do, when authors frequently say 'No, this is wrong'.