Who cares?
One is an just an ass in reality...and not much to it than that. Unlike BPD/ NPD /HPD /AvPD which are just plain fracked between the ears. But the AvPD are quivering in fear. They are quite pleasant.
It depends on the source material.
In many settings vampires that aren't the vampire lord are little more than thralls, zombies with a slightly higher base of intelligence. Pretty much the transformation makes them into little more than henchmen or mooks, having the loss of humanity and soul represented as free will.
If you're going into the "Psychic Vampire" or "Emotional Vampire" nonsense that have been shown in at least one or two documentaries, they're closer to parasitic empaths as opposed to unfeeling bastards.
If you're going by the Buffy model or the Blade model of vampirism, they're like if you gave them a drug addiction and even more violent tendencies with the withdrawal being treated like skin crawling steroids. Buffy's tried to go on about how it shed all humanity leaving behind a murderous husk, but then they started writing exceptions.
In many comics and the like, the trait that's more fixated on is the craving, showing a personality swap when the hunger sets in, or shedding their humanity similarly to how someone going through starvation at a rapid rate might act with a basis of super speed, strength, or more-than-human hypnotic guile.
Interview with a Vampire has too much humanity left intact if you ask me, as does that horrible movie Daybreakers (only redeeming quality is the setting, fuck that fire = life symbolism).
Here's a wiki list that might help you.
Overall, I'd say they show more in common with veteran drug addicts than sociopaths.
Now, if you meant "are sociopaths like those crazy vamp kids we don't talk about", check their forums. They're closer to depressed off-brand gawth people that have more in common with furries and internet Wiccans than sociopaths.
Edit: Right, there's also the sparkly ones. Eugh.