Question: What constitutes a vampire "nest"? Is it just the home of several vampires, or does it have to actually be "nest" like (i.e. dirty, dark, stinky, unpleasant)? 

For instance, I've never seen the Cullen's house referred to as a nest, since they're sort of civilized. But in the first season of True Blood there were three vampires living in a house and it was referred to as a nest. Is there a distinction? Or just the preference of the author writing the vampires? Is Jean Claude's building in the Anita Blake series considered a nest? 

Also, what is the first mention of a 'vampire nest' in fiction?

Answer: 
First mention of the phrase I could find:

Percy MacKaye's "[The Canterbury Pilgrims](http://en.wikipedia.org/wiki/The_Canterbury_Pilgrims)" play (1903)

> 
> Oh, monstrous brood, hatched in a vampire's nest ! But I will be revenged
> 
> 
> 

As far as what a nest is, it depends on the work in question. "Night/Day Watch" series by Lukyanenko defined a nest as vampires initiated by a given "originating" vampire - that is a frequent interpretation.
The first time I encountered the term was in the movie The Lost Boys (1987).