I've heard that. But the "undead" what's with that. If one is not alive, then one has no way of moving as there is no way for the muscles to contract. Also no brain activity. If the drink blood to "unlive" how do metabolize it? If they have no muscle control the blood will eventually leak out their butt. Messy

Also, how does one physically grow extra long teeth then later have them shrink.
It's just crazy.
This all aligns itself with credibility in movies where cars collide with a bus and the bus flies though the air
There are 10 kinds of people.
Those that understand binary and those that don't.