My point was that Neiman-Marcus had a product (properly fitted business suits) that was actually (probably upper) middle class. And that product, in fact, served its purpose really well.
People still underestimate the effect that an excellent suit has on people's perception of you in business. Being tech, I normally cruise around in really casual wear. However, investor meetings demand something a little more upscale so I'm pulling out my nice suit. I chuckle at the difference in behavior of the people around me (both employees and strangers) when I show up for work in a suit.
I'm not disagreeing with anything you said on making a good impression but that doesn't change anything on the fact that Neiman Marcus has never been for middle class shoppers. A one-off purchase does not make a customer base.