What's a good scan?

In my previous post, I talked about failed scans, but what's a good scan? What does it look like? How is it different from a photo? It's a question that comes back regularly when I work on FairScan, and I still don't have a clear answer. What I know is that this question quietly drives many of the strategic choices I make. I recently worked on improving how FairScan handles color documents, and…