Answer:
vampire are not proven to be true...yet. But you can tell because of fangs and usally a very pale face.
(the pace face is true but no fangs they look just like humans and dont go around in castles killing people in black capes)
^ Actually vampires tan really well. They don't show their fangs to anyone unless they feel threatened or are about to eat your face off (lol). A vampire has a Mark of the Order. If you see the Mark, you'll know it's true because you'll want to run away screaming your head off, or you'll probably have a heart attack. The Mark repels humans. :p