I remember watching a documentary about vampires. It appears that little science or even forethought has gone into writing about their habits. For example, the documentary said that in order for anyone to leave the classic vampire bitemarks on a neck, they'd have to use one upper and one lower canine, instead of the traditional pair of upper canines. Otherwise, the distance between the punctures would be all wrong. Besides there would be no explanation why the lower -presumably non fangy- teeth don't leave any marks at all.

just adding to the silliness