I recall a commentary on a stargate episode where they commented that the USAF was always upset if any of the actors didn't follow the rules about hats to the letter.
This is because all of the uniform regulations become second nature to you when you're in the military. You and everybody that you work with wear the uniform in the same way, so it's incredibly distracting and jarring to see it worn correctly. It's actually hard to focus on the show because you're staring at the guy and thinking, "What an idiot!"
Ask any former Navy officer about what was the most inaccurate part of Crimson Tide. Nine times out of ten, they won't mention the submarine's mutiny that almost leads to nuclear armageddon or the underwater gunplay or the electronics technician soldering together a top secret encrypted VLF radio receiver. They'll instead complain about how Gene Hackman's uniform was so screwed up.
