Juliana Smith's column in today's Ancestry Daily News (Seeking Out Images for Your Family History) reminded me of a family story about photo disposal.
It was probably in the early 1950s, when one of my great-grandmothers decided she wanted to get rid of numerous old photos, reasoning that she had no use for photos of people she couldn't identify. While other family was barbecuing, great-grandma put two and two together and proceeded to get a box of photos from the house. Despite one of her daughters pleading not to burn the photos, that's exactly what happened.
There's no telling who was in the photos. I suspect that since she didn't know who the people were, it was likely the photos were either very old -- she was born in 1883 -- or had belonged to her husband's family and, naturally, she probably wouldn't have been able to identify all of his family members. (No one has mentioned anything about Alzheimer's-like behavior, so I assume she really did not know who the photos were of.)