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

When I was onboard the USS Bonhomme Richard I had an XO whom was an O-6 and this man would walk around, while in port and out to sea, with no cover, a faded top khaki shirt, sleeves rolled up to below elbow, no undershirt and a 5 o'clock shadow. I asked my LPO at the time, a PO1, if we could tell him something about his appearance. He told us that we could in a very respectful way but him being an O-6 you might not like the results after that. In the end we just let him be.

CSM O'Black nailed it. Scroll until you find his comment, then read and heed.

Approach not confront.

No one regardless of rank is above Military Regulation or Standard. If you chose to engage with a person of higher rank stay within the military Protocol.

While I was “in” I used to believe so. Absolutely. Now that I’m retired, I think about all those times I “got into it” with someone because of it and think “what was the purpose?”… it really doesn’t matter if you use tact or not, people do what they want and if they are higher rank they will just brush it off, do what they want and all you do is be kissed and ranting about that one a-hole who should have known better. Now, I simply believe that if I was Senior then I would use my influence to change the things I could and not worry s out the thing I couldn’t. It would have made my life sooo much easier not worrying about something so pointless as pointing someone doing something wrong when they just aren’t going to change.

My advise to young “me” would be: do your best to change the things you can and don’t worry about the things you can’t. Less worry and be much more happy.

I'm not sure confront is the word or approach I'd use in this situation. It gives the impression that your intent is to embarrass instead of simply bringing the matter to the person's attention. I would suggest always being respectful regardless of the individual's rank or position.

I can't speak to how or when one would do this in the current military, but when I served it was drilled into my head never "mess" with anyone above you in your direct chain of command. If they wanted to they could not only get even, but get ahead (you could quickly find yourself assigned to every dirty detail that no one else wanted to do). People outside your chain of command were fair game (as long as you could trust your chain of command to have your back).

You are making an on-the-spot correction
Think of it this way, if you don't tell the GEN their pants are undone, they will be a walking disgrace to the uniform and all that we represent

Always use professionalism, tact, and a bit of shaming when dealing with a Superior/Officer who is being unprofessional. Ask them politely, "Would they see and address a subordinate acting in an unprofessional manner?" "Or, Sir/Ma'am aren't you supposed to be leading by example?"

This usually makes them stop and think about their actions in most cases; which they will clearly stop acting unprofessional and expect that their behavior and square it away immediately. It's not hard just needs to be done with the right tone and professionalism.

Yes, but used tact, call her to the side with witness of course and a copy of the uniform code for reference!