Why vampires aren't sexy

They kill you.
Original vampires, the ones people think are real and also come from legends, don't even have fangs.
They're the living dead and therefore share some characteristics with zombies, which, in case you weren't already aware, also kill you.
They don't only go after people. They also go after animals such as cattle. They're not craving your blood specifically. To them, you're just as good as your neighbor's goat.
They have to dig themselves out of their graves to go do their murderous blood-sucking. Therefore, they are filthy and probably stink (even more than they already do, since they're dead).
Due to the fact that they're dead, they very likely have HORRIBLE breath, which would undoubtedly make kissing them (you know you want to) terribly unpleasant. Nevermind the fact that they probably have no sex drive. BECAUSE THEY ARE DEAD.
There are some legends of female vampires that prefer not to suck your blood, but to eat your innards. Specifically, they eat the fetuses out of pregnant women. Oh, that's hot. (These varieties of vampires also eat phlegm. Yes, they are booger-eaters. ["The mucus queen is all yours."])

Give it up.

Also, Robert Pattison has a weird face.