That's exactly it. When we look for the very cheapest possible, we have to expect that we're also going to be dealing with the lowest type employees who must accept the lowest wages, and businesses that don't bother to make any kind of investment in service or training. Those employees then get the rudest customers and their attitude worsens.
I was truly out of place there (this store in particular is located in one of the wealthiest parts of the New York metropolitan area), but I do understand the appeal of a place like that. I didn't deal with a "sales person" -- I dealt with a "sales associate" whose business card indicated that he was a "certified shoe specialist." And several days later I received a very nice thank-you note in the mail from the sales associate who helped me. That's the kind of service you don't soon forget.