I'll give an example of "girl next door" first off Jessica Simpson. She's a beautiful girl, yet everyone talks about her behind her back (calling her fat, dumb, etc.) She's actually a very nice person. And she's very sexy and so, guys are interested in her. And women are jelous of her, (which is why I think they talk about her like they do.) I think she is a classic example of a "girl next door." It's not necessarily a bad thing, but it has mixed meanings and mixed messages.

The "girl next door" is always pretty, the girl who is very sexually attractive, but not necessarily the girl a guy will bring home to mom. And yes, it is used in porn a lot.... for that reason!

As for "small town" it is a town that is usually out in the country, some distance from the city. It has a low population where everyone knows everyone. Generally farming communities and Christian oriented in value system.