Okay - strategy #2: move way out in the country so it costs them a fortune to go door to door.
Never had a vacuum cleaner salesman but we've had door to door magazines (working to overcome shyness and/or fund a trip I think they said), school chocolates, Girl Scouts, and the religious folks.
The weirdest one was the politician that came around the house to the back door (nobody comes to our back door). Surprised DW badly. She was home alone and said he was creepy. Didn't get our votes.