The other morning I was sitting in my doctor's office waiting for my appointment. I sat down and grabbed a book from my bag to start reading while I waited. The woman working at the receptionist desk picked up the phone and phoned one of her co-workers in the back to inform her about lunch in the employee break area. Then, for what seemed like 5 minutes or so the woman was talking to her co-worker about a patient that had been there earlier that day. Phrases like "worry-wort" and "she panics all the time" and other negative things were being said about this patient, including "I was so glad when she left".
While I understand the need for people to vent to friends about frustrating situations, including at work, there is a time and a place for it. This woman was talking poorly about another patient (read- customer) in front of two other "customers" sitting in the waiting room. The lady who was sitting in the waiting room with me leaned over and said "makes me wonder what they will say about us after we leave". Bottom line, this type of behavior from your employees, in front of customers does not instill confidence in your brand. Unless you are the only person on the block or in town with your unique product, your customers are likely to not return based on this type of behavior.
With so many options now when it comes to making a purchase (brick-and-mortar, e-commerce, pop-up shop, etc) it is even harder to get customers to open their wallet and make a purchase. In fact, it is estimated that one of the reasons that consumer spending has declined in brick-and-mortar shops now is because consumers research what they want on the internet first, then go in the shop and pick it up. They no longer "browse" the store anymore.
In order to get your customers to open their wallet, you need to instill trust and confidence in your brand- and a lot of that has to do with your sales staff.