Join Date: Mar 2008
Location: Manchester, UK.
The Good Vampire trope has been something that Warhammer has actively tried to distance itself from, but for more than "ooh, Vampires are evil, look at Dracula, blah blah" point of view of stereotypical fantasy.
The "good vampire" as in Blade, or any other antihero type used to be a thing, back in very early Warhammer - Genevieve Dieudonne was written by jack Yeovil/Kim Newman (same person), and has been used in several books written under each pen name, both in and out of the warhammer universe - however, Games Workshop IP requires that their IP is not used out of the warhammer setting (hence why you'll never see a Games Workshop versus Star Wars game, and the old Dawn of War mods which attempted to do that were shut down).
As Genevieve has not made another appearance in a Warhammer Fantasy novel, she's pretty dead and buried considering that the nature of the game and its fluff has massively advanced in the 25 years it has been knocking about (that series is older than me, yo!), and we've had, at least 4 new editions since then.
I also do not think that the Vampires are capable of "good". The nearest allegory to that are the Blood Dragons - Abhorash, the first of the blood line actively tried to resist the call of the Blood, but that caused him to become near insane with bloodlust and slaughtered much of the city as he fled into the wilderness - however, that is from Liber Necris - an awesome book if you ever get your hands on it - but sadly, with information that's different from latter books - Mike Lee's Nagash for example.
However, the fluff with a Vampire now is that they are changed by Nagash's magic. They must feed off blood to sustain themselves, which is what makes them "evil" in human eyes. If they don't, they risk becoming more Bestial, similar to Strigoi or, possibly, with the aid of Dark Magic, become a Vargheist. Because they are ever living, they get to see the passing of ages, see things change, and all other romantic "ever living" stuff where they see everything they ever knew and ever love turn their attitudes.
They are also a superior form of being - they are faster, stronger, often more intelligent, all have magical prowess (note that magical prowess does not necessarily mean that they are all Battle Mages, though). This basically means that they are dismissive of the lesser humans which colours their opinion even more so, especially when already they are likely to be aristocrats, or members of some order of likely nominal meritocracy (such as a Knightly Order, or College of Magic).
Their attitude is coloured by the older they live, and that they desire to have a purpose for their eternal life, plus especially now with the ever growing call of Nagash.
The one "old" Vampire we are currently unaccounted for is the Eastern Prince Xian Ha Feng from the Nagash Trilogy.
It's not a black and white question really, there are different shades of anal probing,
a rectum spectrum, if you will