They have been known to result in freaky, paranormal photographs of weird-looking dead girls who haunt you! AHHHHHH! (I mean, I understand product placement, but why you'd want it for this movie is beyond me.)
I've only recently begun to experience the paranormal through my 50 mm, let me tell you it isn't a good experience. If I'd known that Pentax's were so prone to "ghosting" when I bought mine I'd have taken another route.
I suppose it's a rare exception when you do in fact need a particular brand to get the image