About alignment:
There is the matter of what do you mean by alignment:
1) Personal ethics/D&D based: In this scenario bloodtheft is definitely an evil act, unless you happen o commit it while in self-defense. Alignment is very rigid and strict, and frankly no matter how many self justifications someone might try to offer devise, conscience cannot be fooled.
2) World view/Fame: In this scenario, it depends whether you are caught in the act, and what type of damage control you are able to do. Even though you might have committed the act in self defense, many will be skeptical, and might consider you a maniac (depends on their own relations with your character and other social parameters). At best you can expect a certain amount of distrust.
I guess it depends on the situation, but once such an act is known, it would be very hard to control the rumors and avoid being labeled as "evil".