There was recently a news article in the Daily Mail about two gentlemen who were declined boarding for First Class due to a dress code. I like to dress in business attire because my slacks are often more comfortable than my jeans and I feel like I am taken more seriously when I do, but I also know that often the worst dressed people in First are often some of the highest paid people there (actors, musicians, other celebrities trying to lay low by dressing down or .com execs who shun business norms) and I never judge anyone in First by how they dress.
That being said, US Airways and other airlines do have a dress code for employee travel benefit users.
First or Envoy Class: Pass travelers may wear casual attire, including blue or black denim attire, skirts, capri-style pants, and sandals, provided it is well groomed, neat, clean, and conservative. Unacceptable attire in First Class/Envoy includes tee shirts, shorts, jogging suits, athletic gear, baseball caps, athletic shoes, beach footwear, flip flops including Croc style footwear.
The men were reported to be wearing jeans, hoodies, and baseball caps. Jeans are listed as appropriate, but baseball caps are not and the hoodies could fall under jogging suites or athletic gear and should be changed for a button up shirt. Employees who allow a friend to travel on buddy passes are supposed to inform them of any of these regulations. I am sorry the men had to experience this humiliation and maybe US Airways will reconsider their dress code since revenue and upgraded passengers in First class do not have a dress code (and that is a discussion for another post!).
The Daily Mail link features a video of the men.