I tend to believe there are less scammers out there than you think. I have bought and sold hundreds of items in good faith. I own thousands of dollars of bass guitars and gear. Every piece was bought by sending a check to some guy I found on a forum and he shipped me the gear. Most of them go out of their way to see to it that I am happy. I have even gotten pictures of packages being handed to people at the UPS store sent to me via phone text (a shipping "selfie" if you will). Also, of all the crowds I have dealt with in the many hobbies/careers I have participated in, ham guys seem to be the most stand up crowd of them all. I am sorry that you have obviously has the opposite experience. If you don't mind sharing, how have you been scammed in the past? Also, if you do have a call sign on a piece of paper in a pic contained within a sale post, it would be stupid simple to contact the guy via other sources. The FCC puts all of our business on the web for everyone to see. You give me a call sign, and more often than not I will have a phone number for you in a matter of seconds. The interwebs are powerful. So, it should be easy enough to follow up on anyone with whom you would do business.