Professional. It brings to mind a neat, dark suit, short (for men) or stylish (for women) haircut, polished shoes, articulate vocabulary. What is interesting is all the very human attributes it excludes. If you want to look truly professional, skip the visible tattoos or flamboyant jewelry; bright shirts or wild hair styles are also out. Don't show photos of your kids. Watch your vocabulary: don't use profanity or "cute" or "cool" or any kind of slang. In other words, suppress all indications of individuality and conform to the specifications so that everyone will trust you to be impartial, regardless of your actual ability.
These specifications are the last remnants of the Organization Man, usually found in the hierarchies that typified Whyte's conformist bureaucracies. Is the dark suit a slowly-fading holdover from the 1950s, or has it become a tribal costume that fills a need in society?