Selling Door-to-Door

Within the span of three hours last night, I had no less than three people come to my front door in an attempt to sell me something. Dear Girl Scouts, Comcast, and WGBH, a few factors to consider when trying to separate me from my hard-earned money:

• Door-to-door sales do not work because they work on your timetable, not mine. 
• If I tell you i'm busy, and have a crying infant in my arms, I really don't want to talk to you. Trying out different arguments won't make any difference.
• If you do your rounds and notice that people in the neighborhood are frustrated because they've been bothered THREE times in one night, it might be time to hang it up for the night. 
• No means no. If I say no, don't keep talking. The odds of me buying your product just dropped incrementally.

Quite frankly, i'm amazed that people still try to do door-to-door sales anymore - it seems inefficient, alienating to your customers, and resource intensive. Is there some success metric arguing against this of which that i'm unaware?