Is it appropriate to confront a higher rank when they are blatantly disregarding regs?

I understand your predicament. Definitely try to enlist someone more senior to address this. Timing of having this to be addressed takes finesse.

I know this is three years old but for the guys who read this later down the line. I as an E-5 corrected on 0-5. It's all about respect. You don't correct the senior, you invite their attention to the regulation in a quiet manner away from any subordinats. The goal isn't to shame them.

If it was the Marine corps I would say abso #&&+:_$8 lutely!!!

I would hope you would take the opportunity to find a chance to ask the question. “ma’am, I love you lipstick but always thought it was against the regulations. I must have missed the change, can we discuss this so I understand better?” We see changes every day and some we may not know and some they may not know. This provides an opportunity for each to learn. If all you want to do is openly confront... it does no one any good.

Tactfully, yes... as CSM Stuart C. O'Black indicated. When I was active, I relied on my subs to hold me to the same standard as I held them and demonstrated to them how to do this tactfully. And no reprisals from me or anyone else and long as they were right and was tactful. Note the last two lines of the Airman's Creed. Add to that, "Integrity First, Service Before Self, Excellence In All We Do". Given the rank differences, I can see how it may scare you a bit, but always uphold our standards to the highest and do the right thing whenever the opportunity presents itself so we can make our Force even stronger.
"ABOVE ALL"

I wouldn't say confront. Such a harsh word. Politely question. Sir/Ma'am, you are telling me to do "X" but the regulation states "Y", could you please clearify.

Seriously? The Air Force has regulations on uniforms and grooming?

We have a warrant who come in galley with socks and his sweaty Tour de France jersey on. It’s gross

Yes, you should make on the spot corrections. Use tact and be respectful. As a senior leader I welcome corrections from a lower rank if I am out of regulations. First off, it's better to be corrected by a Private than a SGM any day of the week. Second, and most important, a Soldier of a lower rank making that correction shows me they are reading and understanding the regulations. We all make mistakes and always should seek improvement. By respectfully accepting a correction, a leader is helping a subordinate and developing the Soldiers courage. Yes, it takes courage for a Soldier to do that, especially in a toxic environment. As leaders, we should not punish or otherwise condemn a junior Soldier for doing this. We should insure the Soldier is correct. If not, a good leader will show them where they are incorrect in a non- threatening manner. They are learning. If correct, acknowledge they are right aND make the correction. Either way, do not be hostile or display any kind of hostility. We are here to develop junior Soldiers and NCO's.

I’m seeing a lot of correct answers.
Make the correction as tactfully AND as privately as possible.