People may not understand the importance of social class in this film...
Many people are complaining about how the costumes and hair in this film are "wrong." That they are not what people would have been wearing in the early '80s.
I was in NYC during this time, at those clubs, with people like the characters in the film. It's close to spot-on. Of course Whit Stillman is going to get it right. He's of that milieu.
I'm thinking, though, that it may make sense that posters who are up in arms about [what they perceive to be] anachronisms just might not have the background to recognize who the characters were meant to be. Unless you were there and among them, you'd would probably have little way of knowing that these characters are based on the sort of people who, in real life, would have looked, talked, and worn their hair quite differently from the far-flung stereotypical '80s manner.
As in the film, people from their social class would not have had big hair or Farrah Faucett feathers or worn "cheap" fashions commonly associated with the '80s. The 1980s was a very class-conscious era. There were clothes that the mainstream could afford and there were the expensive and/or classic clothes (with a teeny bit of a nod to style) that the upper and true upper middle classes would wear. And everyone could tell at a glance where you belonged on the social hierarchy by clothes, posture, hair, accent, tone, manner, etc. Some of that distinction has become more subtle or disappeared over time, for better and for worse.
btw....tasteful off the shoulder dresses were, actually, rather popular at the time, with certain sets -- I wore one to what would be considered a "prom"-like event.