Back in high school I did quite a bit of thinking on this. Mainly because I had way too much free time on my hands. I devised the scientific field of clique techtonics (and later breastology, but that's for another time).
The way it worked in my mind was this: There were two warring factions of popular people, the Preps and the Freaks. They were discernable mainly by color scheme and hair styles, and if you listened to their groupings long enough, you would find that there was little else separating the factions. Those that did not fit into the people generally liked by large groups of people were the Dorks. Dork was an all encompassing term for everyone from the math-whiz to Cletus the slack-jawed yokel. Dorks just weren't well liked by any large group of people.
Here's where it gets interesting. There were two subclassifications that most Dorks fell into. These were the Nerds and the Geeks. They were both made up of intelligent Dorks, but where the Nerds were a severly book-smart bunch who shunned the company of others, Geeks were passably book-smart with a sort of odd specialization. These specializations were generally community things. You had Band-Geeks and Drama-Geeks, Computer-Geeks and Role-Playing-Geeks. Each specialization had its own small community, and within this small community, the Geeks were popular. If you fit into enough of these communities, you really weren't much of a Geek any more (because lots of people liked you and so you didn't qualify for Dork status at all), you were just kind of weird. People liked you but thought you were weird. This is where I aspired to be.
Looking back, I think I achieved that aspiration by the end of high school. I liked computers, role playing games, acting, and Japanese animation. All geeky endeavors. I also invented Clique Techtonics and shared my new findings with others. That certainly marked me weird enough.
This post was way too long, and I never really touched on the Geek-Posers you were talking about. (Which have to be the lowest form of scum this side of ... er. Something scummy.)
\/_ Dorktastic! \/_