Patrick MichelsA show of buttoned-down professionalism, typical of the restaurant business, at the Seat-B-Clean booth.The Southwest Foodservice Expo, in the Dallas Convention Center last week, was an sprawling, facsinating deconstruction of the business, as if some omnipotent conventioneer had taken apart a restaurant piece by piece, and laid it all out, labeled, under a grid of fluorescent lights.Strolling around the convention floor, you could sample wines and cheeses (separately), get a massa