This does not apply to the Toreador, those fuckers are definitly horny despite also using their sexuality to their advantage.
O'rly? Because my understanding of vampires (at least in Vampire the Masquerade) was that vampires are impotent, although they have the option - or had, when I was last reviewing the rules - to pick a skill that allows their sexual organs to work. At cost of blood (which is more important to vampires than anything else). Also, feeding feels better for them than sex does for humans, so it's questionable why a vampire would prefer to have sex over drinking blood, unless they'd want to manipulate a human. But I am interested to see the evidence to the contrary.
Vampires as a being of Mythos are linked to sexuality ever since they came up again in the 1800s-1900s. Mostly as a sexual predator type thing, although there are some out there theories about Vampires being a class metaphor.
At this point I am not sure what you're getting at. While vampires in Vampire: The Masquerade are indeed predators who are part sexual fantasy in human imagination (this much is true, but I never said otherwise, so... *shrug*), they are also asexual.