I live in a high rise so I never come into contact with door to door sales people. I think everyone in awhile my parents will have someone knock on their door to ask if they'd like to switch to a "green" energy source or if they'd like to upgrade their internet. I think that door to door sales are down and will probably be non existent sooner rather than later, but one thing I have noticed is that there are a lot of "marketing" jobs posted on the internet that appear to actually be door to door knife sales or medical home devices.
The internet pretty much ruined the "Door to Door" Business model. And why wouldn't it? In your example with the vacuum cleaner guy, he spent a long time at your house trying to sell one cleaner. In that same amount of time on the internet, he could he could have advertised to countless more people and gotten a lot more business. Not to mention, you're saving on travel costs and people aren't generally very trusting or willing to listen to people who come to the door these days anyway.