Since when has dressing like a slob while on the job been a 'Right'?
------
It's called blending in and is not deemed a right. I still ask whose ego are we stroking because at no time has any airline required Air Marshalls to adhere to a non-rev dress code. And where in your reading did you decipher that Air Marshalls sit in first class? And don't say it's logical because the whole thread is about lack thereof.
Do you KNOW this, or are you simply saying this? I know that non-revenue passengers MUST comply with this rule; and as Air Marshals are non-revenue generating, a dress code would be expected. I don't know about every airline, but I do know that Alaska and Delta have dress codes for non-revenue generating passengers.
Dress codes for a given profession are nothing new. In some professions, it helps observers differentiate job functions. IF the bad guys expect Air Marshal's to be wearing a sportsjacket; then every businessman in a suit (and there are A LOT of them) is a potential Air Marshal.
When you are speeding down the road, do you hit the brakes every time you see a car that 'LOOKS' like a police cruiser, or every time you see a car? Decoys have their place.