Not necessarily, I've tried to find out whether vampires are real or not and I give people that consider themselves such the benefit of the doubt just because of how dedicated they are to their claim. There are people on this site who've claimed to be vampires and have received nothing but harassment from most people demanding that they admit they're lying. Despite this, these people stick very close to their claim. I think blood drinking vampires probably exist, though it is entirely possible that many people are not one but think they are. I've found some info on "actual" vamps from this website:
This isn't some weird website for posers, it provides believable information and denounces nearly every myth about vampires.