I would always have preferred non smokers and non drinkers, just for safety's sake, but the vegetarian thing I've not heard before. Wouldn't you think it would be the other way around? That meat eaters whose blood would have more iron in it would taste better than those vegetarians who are usually deficient in iron?
I'd have thought you'd have to have very refined taste buds for the blood type to make a difference, but then there is always someone who will post to say they have them, so I'd better shh now. lol
I wonder what the difference is between males and females, is it sexual connection that makes the difference perhaps?
That's an interesting theory.
Would a heterosexual prefer the opposite sex, and a bi-sexual not have a preference, and by the same token a same sex oriented person prefer their own sex to feed from?
Don't mean to insult anyone, I'm just rambling and wondering.

Moon.