In the business that I am in, it involves a certain amount of intestinal fortitude. You need to be able to have 100 doors slammed in your face, figuratively (sometimes literally), and keep on trekking as if nothing ever happened.
When I do meet someone that seems genuinely kind at the door, I try to make a mental note that when I call them, they should be the same nice person...WRONG!
Case in point. I knocked on this nice older lady's door. She invited me into her home, offered my a cup of coffee as it happened to be quite chilly that day. We spoke for a few minutes, she told me about her family, then I went on my way feeling quite good about this prospect. When I phoned her a few weeks later, she was so rotten to me on the phone, she must have woken up on the wrong side of the bed right before someone pissed in her Cheerios! It was awful!
I've learned in my time in sales and customer service that you can't really judge someone right out of the gate, you have to get to know them a bit more. Most people I meet that are nice, remain nice. It's just the rare case where you just get your socks blown off once in a while.
Oh well, it's just the nature of the beast I guess. It just makes me enjoy the nice people that much more.