I've heard them called "vampire shaggers"; I prefer the term "nosferotica" but I can't seem to get it to take off.
I'd much rather we didn't have to call them anything at all.

But yes, if there was a genre called Nosferotica, I may be tempted to pick one up one day.
It depends on the characters, but certainly, there is a specific flavour of humour that people in dangerous jobs often develop to help cope, and more of that among urban fantasy characters in similarly dangerous situations would be appealing to me.
Exactly. And that sense of humour is what helps us in real life, when things are not going exactly the way we want them to. Why should any character in a book be different? Because that's how you care about characters in books, when you can identify with them, be it one trait or all of them.