In order for you to say what a "fake" gangsta is you have to have a clear definition of what a "real" one is. I think it all depends on a person's perspective.
My definition of gangsta would be someone that is down for their friends when they're being wronged. Like that old school mob shit. You fuck with one of us you fuck with all of us. Also it's someone that does good for the whole of the pack not just themselves. Someone who respects those who deserve respect. That old school knight shit. Someone who has nothin to prove because they are sure of themselves. They don't talk alot of shit to build themselves up around their friends (unless their just fuckin around) only their enemies etc, etc, etc. They come in many shapes, many sizes, many different backgrounds, many colors of skin, many different languages, many different cultures, but they all have the same goal.
"You are here because you believe in right and wrong, good and evil, and you choose to do good" - Al Pacino, The Recruit
"To free the oppressed." -Special Forces Motto