I had a funny experience last year going door to door... I realize some have no issue, while others despise it. Nevertheless....
As I'm walking down the driveway from just knocking on a door with no answer, a car is pulling in the driveway. The guy rolls down his window and asks if he can help me? I introduced myself and he got super super irritated. I'm slightly perplexed and he said it's private property. I said I apologize. He then went on to ask why I didn't obey the sign? I told him I didn't see it, otherwise I would have. Again, he got more agitated. So I said OK no problem I will leave.... but sir, are you interested in any landscaping services for 2012? He about flipped! I got a chuckle. As I'm leaving I turn around to find the sign I missed and there was a small sign about 5"x8" sitting in the garden about 20 feet to the right of his driveway that said no tresspassing. It was so damn small I didn't even notice.