Excellent question: How would I ever know? If you never came to the platform there are still ways you may know. In our tiny test market(tiny is 4 sales), all four buyers came from our unique yard sign. All four sellers came from word of mouth. If 1000 properties in your are listed, that suggests 50 will sell in a year. How many would use a PropBox ad is unknown, but you may see a yard sign. I understand you logic and believe some will not come back. But lets see what it looks like in six months.