I rather admire the 'kick the customer's house and tell them its falling apart' technique. It may work. I once had a knock on a door from a jobbing gardener who berated me for the frightful state of my front patio, suggesting that my weeds were putting the whole neighbourhood to shame and that everyone in the street was talking about it. But she could fix it all for two hundred quid.. I was so astonished that I almost agreed. Completely lacked the presence of mind to ask her whether randomly knocking on doors and hurling insults at the occupants normally had the desired effect, though it would have been interesting to know.