From TV Tropes and their article on "fan dumb":
The Perfectionist: Like the Purist, the Perfectionist believes there is only one way to do things. However, whereas the Purist is hung up on a particular period, the Perfectionist is consumed with a particular way of enjoying the product; there is only one correct way to play this game, or listen to this music, or watch this film, and that's his way.
Every time the subject of fansub preferences comes up it's only a matter of time until someone lands slap bang into this definition :anime: