re: What makes a great gumbo?

Two friends of mine that live in Houston (one from Laffy, the other from nola) swear there's no difference between using store bought roux. They are also talking big game about cooking and perfecting gumbo. One of the guys I don't know as long, the other guy I lived with for 5 years in college and I never once saw him try and cook a gumbo (or red beans, which he puts a roux into, which I don't understand at all either). I just went with it and kept eating crawfish and drinking beers. This is all only surprising to me because otherwise he's a better than average cook (which I suppose isn't saying much all things considered).