Why do some members stiff me?

Dang just got burnt again but just a little. At least there was no money involved. I talked to a guy via e-mail for 2 weeks. Started out asking do I have the rubber pieces on the rear of the doors right at the glass. Answered yes. then he want the other two on the front of the quarter windows. I answered yes. Then do I have a good drivers non tinted door glass. Pulled one out of a door,cleaned it and wrote him back yes. Researched shipping on everything and sent him an e-mail with a total. He said I'll take it. Then asked if i had a pair of inner fender Shields. After all this says nah i don't want it. ARHHHHHHHHHHHHHHHHHHHHHHHHH!