I answer the door. If it's neighborhood kids that I know, I'll buy whatever they're selling to help support their sport/activity/school. If it's anybody older or selling for any other reason than a youth sport or activity, they get sent packing right away. I've got no problem whatsoever making it short and decisive that they are wasting their time with me. I do the same thing with phone sales- tell them that I'm not interested and hang up on them before they can get another word in. My wife will ignore the call and let the phone ring, I'll pick it right up and I sort of enjoy being a rude d!(k. I pretty much despise phone sales people. At work, I will usually throw in the request that they remove us from their call list. I think it works sometimes.
I actually scheduled a business consulting firm to come meet with me. They had called numerous times and were very pushy. They were based out of the Denver area (we're 50 miles north of there). So, I finally said "yeah, come on up, I'll meet with ya". When Mr. McDouchebag arrived I simply asked him if they would quit calling us now because every time they call, I was going to schedule them again and didn't care how many trips they wasted. These business consultants are the absolute worst in my book. Still get numerous repeat calls from a few different ones. I'll tell 'em to F off whenever they call.....but they still call back more. Slime of the earth IMO.