Money laundering operations still need cash flow - otherwise there is nothing to launder. Typically they are businesses that actually have lots of real cash flowing. Businesses that have money come in the form of traceable transactions - like credit cards, debit cards, cheques etc, are very difficult to launder money through, as all the money can be traced. But if your prime business is in cash you can claim any amount of income in the door as legitimate trade, and thus can convert that cash into clean money. As society becomes more and more cashless it gets harder. Here in Oz pornography shops still trade, yet it is hard to believe that selling porn magazines makes anyone money in the age of internet porn. But I bet nobody paid in cash when they were making money, and it would be a good business front to claim most income was cash.Betting shops are another.
Given the margins on such dresses are close to infinite, you may only need to sell one a day to stay in business. Salespeople in these shops are pretty good at sizing up customers, and usually claim to know if someone is a timewaster within seconds of their entering the store. They know almost everyone who passes is not in the market for what they are selling, so they don’t care. The ones they are worried about are those that are entereing the store with clear intent. They can turn on the obsequious charm in spades, and know how to woo the money out of their purses. Many customers will be repeats. Many will make appointments.