Growing up with no pets other than a sister, it’s a special occasion when Duke comes to visit. This pup has been around the block once or twice. He’s a rescue dog that was adopted and returned by three families due to bad behavior. He gnawed on leather couches, disobeyed commands, and wasn’t properly potty trained. With an unhealthy record, a fourth family was willing to give him a chance. They believed he was a diamond in the rough. By coming up with a comprehensive set of rules, Duke quickly turned into a well mannered dog. It shows that you can teach an old dog new tricks. 
We can all learn from Dukes experience. Make sure everyone is on the same page and there is no gray area. When customers and employees know what to expect from you and vice versa, it creates a lot less confusion. If someone does cross the line, the worst thing you can do is have no conversation at all. Doing this will make the person think their actions were tolerable. The best way to confront them is in a very neutral manner that is not intimidating. Show them you care and they will give you the respect you need.
Never forget everyone makes mistakes. A lot of the time we don’t even know it until someone else points it out to us. Take the time to lay the ground rules and get everyone on the same page. Instead of delving into someones past, look at all the possibilities of giving someone a second chance can yield great results.