At least on my instance, the top right hand corner on all thumbnails has a little symbol that shows if it is a “link picture” or an “expandable picture.”
The link symbol looks like a box with an arrow, the picture symbol is the generic white outline hills and sun symbol it seems like many places use for images.
Doesn’t really answer your question directly, but it might help?
People who do this professionally, or even as a volunteer, receive training for a reason. It is likely one could hurt more than help, despite the best intentions.
Maybe try signing up for a hotline? They’ll give you the training required to at least give a solid attempt as well as more rationally limit the amount of people you feel obligated to handle.