When and why should you get dress mess?

I was a SFC in the US Army when I purchased the Dress Mess uniform. I did it because I truly believe that if you are a Senior NCO then you should not attend any ball or formal function in your Class A uniform with a bow tie. In my opinion that is not what a Senior NCO should do, that is what the lower enlisted do because they don’t have the money. But at the Senior levels it should be required, just like in the US Navy. Once an NCO gets promoted to Chief, they are expected to have such uniforms.

To me, it's more of where you stand on etiquette than where you are in your career. I was married in evening mess blues, and to me, it was worth every penny. A proper black tie or white tie ensemble is very striking, and should be worn with confidence.

When an invitation calls for black tie, etiquette calls for more than a suit with a black tie. Black tie is a strict dress code which mandates a tuxedo with a black bow tie (absolutely not a four-in-hand tie). Tuxedo lapels are also different from suits, as they are not notched. If you are to attend a black tie affair, and would like to represent your service, or the event is of a military nature, the mess uniform corresponds to the tuxedo. If you are to attend a black tie affair, the ASU simply will not do; it would be poor etiquette. The Class A uniform corresponds to business attire. Although we wear a bow tie in the Dress Blues variation, I would venture to say it corresponds to cocktail or formal dinner attire, which by etiquette is a bit flashier than business attire, yet still lacks the formality of black tie. Only white tie (AKA: white tie with tails, or "full fig") is above black tie in formal evening wear. Corresponding to white tie with tails is the "evening mess" variation. As the most formal attire, it is extremely rare, essentially limited to presidential or royal galas. So, unless you opt to wear it for your wedding, it's unlikely you'll ever wear it. An advantage to the mess uniform, however, it's essentially black tie and white tie, in one purchase. Evening mess is not an expensive variation: only a tie, shirt, and vest. If you're attending someone else's wedding, remember it would be improper to outshine the happy couple. So, if you're likely to be the only one in uniform, it may seem peacockish, especially if you're not in the wedding party. On the other hand, when the other gentlemen look the same, your mess uniform will be distinguished, and will always outclass a rented tux.

I'm in a group on FB of Army officers where the prevailing wisdom is to buy them once you become a field grade officer, or if you're an aide. That might fly for active duty, and I'd suck up and deal if I were active duty, but for the Army Reserve (or the Guard), if you're TPU (M-Day to Guard personnel), it just doesn't pass the common sense test.