people who take photographs of flowers, birds, insects, etc, and post them in a huge collection, hundreds and hundreds, carefully labeled sometimes as to where and when, but not a single
identifying clue as to what those birds, fish, insects, ARE. no names.
I found an image in one of those groupings that was a mate to an insect I had taken a shot of, here in the yard. Utterly useless, except to tell me that I don't have a rarely seen bug. I was so annoyed by this, I actually wrote to the guy and suggested maybe a bit of research would be nice--if you're going to bother to take the picture, you should take that extra step and find out what it is. He said he knew a lot of them, but never got around to putting up the actual names.
Yep, that's useful.
The other peeve I have about photos is lifting stuff from the net with no acknowledgement or identifying clues, just because you 'like the photo'. At least identify what it is, or who it is, when you post it, if it's got markers.