Even Greener Pastures

Interesting, Jerry. I'd say it was the other way around.

How about "German"? Isn't there a difference between introducing me as "This is Susanne. She's a German" and "This is my German friend, Susanne"? Being presented as "a German" would make me feel that this was seen as my defining quality, I'd much rather be introduced differently. Is that just me?

Irena, your example won't wash, sorry. Vegetarian, vegan, gay and German, for that matter, all work as both nouns and adjectives, while a vampire is always a noun. The adjective would be "vampirical" or "vampiric".