Earlier quoted context omitted.
> For example know why not to wear "brown" shoes in town to an interview for a high paying job / internship. Why?
Because it shows that you don't know the rule not to wear "brown" shoes in town to an interview for a high paying job / internship and thus are not of the right class to get a high paying job / internship.
Question: do upper class Americans eat with fork in the left hand and knife in the right? Because I notice most everyone in America that I have met eats with the fork in the right hand, and I am almost unable to eat that way (except dessert).