Those that knock on your door?

Not just religious groups, sales people, etc.
How do you deal with them, what tactics?
We have been getting a ton of them around here lately for some damn reason.

No, I do not want you to show me that cleaner on my car...

I used to work shift work and had a no solicitation sign, so I have real issues with these people.
I think this and phone solicitation should be illegal if uninvited.

I try to be polite, but am forceful if they do not listen after the second or third time. I miss our old place, we had a timer for the sprinklers on the back porch.