You can certainly be a monster of immorality when you’re flawlessly dressed; witness the royal courts of the eighteenth century or the splendid tailoring of the Nazis. But do you see that there is a continuum? It’s difficult to talk about integrity, financial probity, and a sense of high honor to a kid in your office who is sprawled at his desk while wearing flipflops, raggedy cut-offs, and a Che shirt. The reason is that if you reject society’s longterm standards and norms in your speech, manners, deportment, and clothing, you might also reject its norms of other behavior.
In other words I draw a distinction between people who dress in typical American casual style—khakis, boat shoes or sneakers, a polo shirt—and those who dress like real slobs. When you dress like a slob you’re sending a message that says “I don’t care what’s considered good. I don’t care if my hanging armpit hair falls into your food. I am selfish and have an overdeveloped sense of self-esteem, and I will shake my hindquarters and all associated cellulite because I’m ready to have sex right here, right now.”
I draw a further distinction between the truly ignorant and the deliberate slobs, too. There are some people who act and dress like slobs because they really don’t know any better.
I do, and that continuum is where I suggest we find the relativistic aspect of manners and need to dissociate them from morality—except in extreme cases such as those you describe in your previous post.
In the interest of full disclosure my career has been in advertising and design. In many agencies there is often a dichotomy between those who do the "creative" work and those who sell it. Those who create tend toward the flip-flops, cut-offs and Che shirts. (I work both sides, but my primary place has always been on the creative side, and I can guarantee you will never catch me in a Che shirt.)
Though the creatives will deny it, their sense of fashion is just as much a uniform as the suits worn on the account side. At least in my field it is not that difficult to discuss integrity, financial probity and high honor with the kid. Had he come in to the office to interview wearing a Hart Schaffner & Marx, or Hickey Freeman suit, he likely would not have been hired. (A dressed down Hugo Boss, or Joseph Abboud, maybe.)
For both groups there is a code. Interestingly though, the sense of integrity, financial probity and high honor is more likely to be found among the creatives instead of the account types. As you suggest, flawless dress is not everything.
As for armpit hair hanging in food, I would simply find another place to eat. As vivid as your description is, I really don't see that too much.