Zero.
I'm a werepyre, actually.
And I only sparkle when I wear glitter or jewelry (or a twinkle in my eye, if that counts).
But I do like the Twilight saga. When I read the first one and he went to show her what he looked like in the sunlight, I have to say I wasn't expecting him to sparkle. I've accepted it as part of the story though...it doesn't really bother me.