I released a simple mod to fix the race detection problems with vampires. It seems Bethesda forgot to add in checks for if the player is a vampire variant of their race (the game checks for nordrace for "hail kinsman", but doesn't check for nordracevampire). As I said before, this is a simple mod purely aimed at a small niche audience but I'm hoping people will enjoy using it.

It should work for most NPCs, but there may be a few which still need changing. If there are, please feel free to let me know and I'll get on it asap!

Mod: http://skyrim.nexusmods.com/mods/42034/?

I hope you enjoy!

Are these reactions based on your stage of vampirism? Like if you are well feed no one notices you are a vampire and as your stages progress their reactions change by degrees (instead of vanilla where they go from normal to murder)?

No, it's just the passing phrases people mutter about your race, like the guards referring to your race when you walk past or elves saying "hello brother/sister elf", etc.

Since you asked

The USKP has had this particular issue fixed since version 1.2.1.

So it does! I'll be sure to edit that out of the OP then, thanks for the clarification. I was sure there had to be something else that fixed it out there.