Evil is a subjective concept. To a human, Vampires may seem evil. To a cow, Humans must seem evil. Us Blood Dragons live by honor, and courage, many of us hailing from Bretonnia itself. To not fight the beast within is to become a Strigoi, as you can tell by our appearance, we have not yielded to the beast, the beast yields to us. If that's evil, then sure, we are Evil, by your subjective definition of it.
This is another type of evil. Brets are misguided to say the least and blindly pursue a course of "noble" deeds. It is just a shame they see it fit to steamroll the rest of the Brettonian land. Peasants only live to feed the nobles, and they continue to do so once the knight become a vampire.
As we're speaking of subjective definition, I dont agree. I think we've got a pretty objective definiton. It is useful to apply the human definition since even though undead, a vampire was once human. But yeah, good and evil is subjective.
But like Voltaire and others now have stated, the so-called good vampire is the exception. For all the self-loathing, honor, virtues, good deeds a vampire perform it does not cancel out the dead corpses that can be found in its trail.