The ones that come around here are very reasonable, I tell them that I'm not interested and they thank me for my time and leave.
There were a group that came around where my parents live and they were very hard to get rid of, I got fed up and went to close the front door when one of them put his foot in the door so that I couldn't close it. The dog took exception to that and made it clear that either he removed his foot from the door or she'd remove his foot from his leg. Good girl.