This has become a huge problem in S/E Wisconsin. Telling elderly their tree is going to fall on the house. Living in a travel trailer around the block. Hooking and pruning oaks in the middle of summer. Starting projects getting paid then leaving without completion. My favorite a guy claiming to be my company. Nothing against the state but around here they all travel from Minnesota. I don't know if they wore out welcome there or what.
I did a little door knocking, I was exceedingly careful to not come off as pushy, just to introduce myself, leave a card, ask that they call me if they didn't already have an arborist and needed some work done in the future. Honestly it was kind of a waste of time, didn't get a whole lot out of it.
Expectations have to be in line. Marketing is successful when you get a response of even 2-3%. I did door knocking when I first moved here and landed 2 clients from it. They connected me with a major client who then promoted me to dozens more. Did it pay? Oh yeah!
It is illegal to door knock/solicit in my local small suburb town. I did it when I began, now I call the cops on them all the time. We have had a rash of thefts in my upper middle class town last year. Having random people wander around unchecked....not kosher imo anymore.