I agree with Fyraltari. While the characters in the story should not believe anything Durkula says, not all liars always lie.

Narratively it makes no sense for the author to intentionally misrepresent the mechanics of his universe. It would be an interesting approach to create a false picture in the readers' minds which is later explained and corrected, but that, in my mind, risks the whole, "Its a dream," issue in which readers feel cheated.

After fifteen years of OotS, Rich has yet to leave me feeling cheated.