I get occasional vendors knocking on the door, everything from roofing and windows guys to lawn and bug guys. Always the same pitch: "We're working at a house in the neighborhood, we'd like to schedule an appointment to come over and discuss your needs."

My answer is always the same: if you have a card or brochure, let me have it and I'll hold onto it. They literally never have anything written to hand out. Usually, the guy says he just does the scheduling, so doesn't have a card.

What exactly is going on with these guys? Some are pretty professionally dressed. I've owned houses for 18 years and have talked to probably a couple hundred of these guys. Are they straight scammers? If not, what's the business model that doesn't want to hand over a business card to someone who might use it a year from now?