Some people will always be bitter, no matter what. (For all you and your wife know, the "locals" hate her, too.)
I think it's more about the "permanents" vs the "transients", no matter in what vehicle/dwelling they live. A permanent resident has no stake in being more than passingly-friendly to someone who will be here today, gone tomorrow. Why make friends with someone only to see them go?
If I were your wife, I wouldn't spend any more energy on this broad and others like her than it takes to feel sorry for them. Anyone so unhappy that she has to be nasty to strangers is living a very miserable life, indeed.