I used to work at a lawn care company as a door knocker (and later on a supervisor of door knockers)
We would walk from house to house trying to get people to sign up for a free estimate (it's just a phone call telling them the price based on the size of their grass). Some people would forge all the signatures, or for those that were rude. Some people would say "Sign if you DON'T want a phone call"

or "Sign if you don't want us to ever come to your house again". My friend would troll all the non-english people all the time, telling them things like "You will get a free coat on your lawn/in your mailbox if you sign"

I never did anything though and all my signatures were real
Tip: If you get a door knocker asking for a phone number and signature for a free quote/estimate, DO IT please

(if they seem nice though). All you have to do is say you're not interested and that you have another company already when you get the phone call. Plus signing will stop door knockers from coming to your door another 3-4 times that season. Plus the doorknockers get paid commission, and it is a hard job with lots of angry people, so do it

I don't know why so many people are terrified when they hear the word "signature", I mean it's nothing.
Some people are stupid though, they would take my clipboard from me and scratch their names out. LOL it's just a printout from the office

Plus if I don't get any signatures on that sheet it just gets thrown out, your name will not be removed from the system.