You also have the right to order them out of, or deny them entry into, your house. They can come in with a warrant of course but there are situations where they don't have to have one.
As a business, have you received an out-of-town or out-of-state order, the "customer" then pays with a bogus credit card and you end up getting ripped off twice? It happens all the time, and today Texarkana Texas Police are sending out their latest Scam Alert on this very topic.