I would not buy anything from a store where the owner says something rude to ANY customer who just walked in. I was taught that you can cut your shoplifting losses greatly by greeting everyone entering your store and asking what they need today. I don't think it would cut down shoplifting to be rude but you would save time as you would eventually lose all your customers. If you are worried about 'wasting time' on people, don't own a retail store- it is mostly what a store does.