We have one of those no hawker stickers by the front door. Doesn't stop some people chancing their arm. A polite no thanks and a quick door slam gets the message across
20 years ago when my lad played kids football, one of the other kids dads did door to door selling. He openly admitted scamming people and made a fortune. He never even batted an eyelid about it. Used to drive to the other end of the country staying overnight in hotels.
Had one at our door a couple of months ago. Turned very nasty when I said "no thanks". Started calling me all sorts, and when I told him to beat it or I would call the cops, he told me I was a "f... grass"! Missus came out to see what all the noise was about and she got a mouthful too before he went on his way. I did call the police on 101 as we've got a lot of pensioners on their own round here, asked them to come round to chase them off, they never showed up ...