Sixty years ago when I did my first sales course in retail, we practiced greeting customers with Good morning Madam your lipstick is smudged" We then had to try that for a week and report back.

The aim of the lesson was to demonstrate that in almost all cases, the customer is not listening to your greeting or is silently going over what they want to ask. In most cases they will say thanks regardless of what you say and then ask-------. In some cases especially women they will get flustered if you break their thoughts and they could walk out. We were taught to greet with a smile and to say nothing.