There have been two bugs with vampire's appearance that have not yet been fixed,

1) The skin tone for Imperials, Bretons and Nords changes to a tanned rather than pale complexion(did Bethesda even bug test vampirism?)
2) There is often a head/body colour mismatch, which isn't specific to vampires, but it does plague them more than others

I did a search for "vampire" & "skin" before i made this topic, and was surprised to see only about 5 results, and none of them related to the bugs i mentioned.