I think what the other guy means by "poser" is someone who is not a motorhead, gearhead, etc...has never really been a car fanatic (like most of us). That person comes into money (nothing wrong with that!) and decides he should buy a cool car (Ferrari, Porsche, etc). The "poser" is usually very unknowlegable about sports cars, and is just as likely to trade for a really expensive SUV the next time. I don't think there is anything wrong with this...it's just a different kind of owner. When you engage them in conversation because of their car, you can quickly see that they don't seem very knowlegable about cars.
Another definition of "poser" is someone who drives a car that (in some people's opinion) is more expensive than they really should be driving, thus giving the impression that they are rich (or richer than they really are). This is thrown around at people driving entry-level, barely leased, or older used BMW's and MB's a lot. I don't buy this definition. "If you didn't steal it, you deserve to be driving it."
It is human nature to cast dispersions on those who have more than we do. We think we deserve that 360 more because we know the bore and stroke dimensions, and that dentist doesn't even know what a 333 SP is. Remember, "It's all good!"
Now, off to watch the 550's kick Corvette butt at Petite LeMans!