Alba many years ago on holiday in Welsh Wales at the bottom of Snowdonia Railway in the souvenir shop was a placard for sale that said :-
We dont want double gazing,home extensions,life insurance,home security,cavity wall insulation,religious groups, new kitchen,central heating, financial advice, or market research.
DONT KNOCK.DONT RING.DONT CALL
look at that I said to Chief Stout and he said if its still for sale when we get back from the train trip up the mountain I will get it for you and he did and we fixed it in our porch along with "beware of the dog" in english, beware of the cat in portuguese, and our house sign "The Hovel".
We still get the odd cold caller but I just point to the notice and say "cant you read pal" and shut the door.
smug buggers us !