Yes, I know you know. Door-to-door marketing doesn't work. It used to work because personal, unannounced and in-person calls used to be expected and commonplace. Now, an unexpected knock on the door is cause for alarm, rather than curiosity. On a basic level, any type of intrusive marketing, in-person or otherwise, can have more negative than positive effects on your business. In most cases, the same concerns are amplified if you happen to be knocking on the doors of businesses.
Consider what door-to-door or other intrusive marketing says about your business. Consider marketing efforts that are not "one by one" oriented. Consider the fact that marketing forums, channels and opportunities have never been so nuanced, sophisticated or targeted. Put away the shotgun and pick up the sniper rifle.