>>Go to the back door (most salesmen go to the front door, a manoeuvre always resented by maid and mistress alike).

To most of us Yankees, this makes no sense. Many of not most of our single-family homes are built in areas that don't implement an alleyway, so the back door is really only for the residents to get to the back yard or carport, etc.

If a salesman knocked on the back door it's likely they'd have the police called on them / or worse.