Throughout my life I've worked in a variety of fields and industries. I even had the pleasure of working as a commission door to door sales rep for a large company many years ago. Believe me when I tell you that door to door sales is a very tough job. Getting rejected on a regular basis without taking it personal is difficult. The fluctuation of income can put you in the presidential suit one week, and in a card board box the next week. I commend, and respect those of you who choose this line of work. It is not for everyone. With that being said, let me tell you how to deal with door to door salesmen.
First of all buying anything from street hustling door to door salesman is risky, and usually not worth your time. If you really want a good deal, spend some time researching the product online and finding the best price. Kirby might make a great vacuum, but I feel awkward buying something from the trunk of a 1987 Toyota Camry. I would much rather buy a Dyson from a store and be able to return it if needed. If a product is really that great, odds are you can find it elsewhere for cheaper.
After opening your front door, you can usually tell if someone is trying to sell something within the first 5 seconds. Is the person holding anything like a clip board, or wearing a shirt with an insignia on it? Is he standing at the door, or back a few steps? Do they instantly start in to a long winded speech. Identify a sales man is easy, how you spend your time after that 5 seconds is up to you. You can either listen to the entire monologue of previously rehearsed sales pitch, or you can politely take control of the conversation and end the sale. There is no point in wasting time for either party.
The simplest way to end a sale is to thank them for the opportunity, and politely close the door. Don't be guilt tripped into hearing them out. The longer the door is open the more of a chance they have to charm you into purchasing something. A good salesman will continue to sell as long as the door is still open. The trick is to be tactful about it when closing the door. You don't want to anger the seller to the point that he steals your front lawn gnome and smashes it in the street.
It's difficult for many people to close the door on a Girl Scout selling cookies, or a kid fundraising for his school. Personally I would much rather buy cookies from the Girl Scout Troops' stand at the grocery store. That way I am not bothered at home, and realistically young children probably shouldn't be encouraged to go to strangers houses anyway.
Whether it's rain gutter system, cleaning products, magazine subscriptions, or donations for world peace save your money and close the door. It's just not worth it.