Among the pictures I am digitizing and organizing are some of people I cannot identify. That's one problem that we all face. What makes it a particular concern is that pictures come down to you from Relative A who may have inherited it from Relative B and it's B's in-laws, and not your family at all. How do you know?
Another set are pictures that are not my family but are identified on the back of the photo. The solution here was advised to me by the Practical Archivist. She said to upload it to Dead Fred. Evidently this is an orphaned photo site. Much like Findagrave, it is operated by volunteers uploading photos. So I uploaded two that were clearly identified. You can search Dead Fred on the other side too to find pictures of your long lost ancestors. I did a broad search for the surname Pinkham and got two hits. They were both group photos with men named Pinkham identified in the group. Neither were any close relation to me. The other surnames I searched all came up empty. At present there are just over 100,000 photos in Dead Fred according to their website.
From what the Practical Archivist told me and the promos on Dead Fred, people have found pictures of their ancestors that they might not have found any other way. So Kudos to Dead Fred. My next experiment will be to upload a purely unknown photo.
I told the Practical Archivist that I wanted to destroy the pictures I couldn't identify because I didn't want the next generation to be confused as to who might be in the photos. It was then that she told me about Dead Fred. I didn't have the heart to tell her my grandmother went through her photo albums and removed and destroyed all the non-family pictures, because she said, they had no meaning to anyone but herself. I know this because I watched her do it. Had there been an Internet then, I might have saved them and found out if anyone wanted them. Now we can.