Some people think it takes a special sort of person to make a success of buying or selling. It is true, some people have the knack. It’s like the lad who came round, he was selling plots in the local cemetery. So we got rid of him by telling him that we’d already got one. He just smiled politely and said, “Well I hope you’ll be very happy there.”
But the main thing that marks out somebody who is going to get the sales is their attitude.
To quote an exchange from a truly fine work of literature;

Horfin laughed. “Take no notice of Chi Tah. He will buy or sell anything.”
Chi Tah bowed. “Indeed I keep my grandmother freshly washed and presentable against the possibility of impulse buyers.”

http://www.amazon.co.uk/The-Flames-City-Cities-Gods-ebook/dp/B00BLQAAFM

But on a serious note, any author can sell their books to people at a show if they stick…