Most of the time when someone posts a picture, the subject (or reason they posted it) is pretty clear.

Comments that are appropriate include: 1) comments about the subject/point of the photo, and 2) comments about something else in the photo as long as they're complimentary

or positive.

Comments that are not appropriate: 1) any negative or critical comment regarding something in the photo that has nothing to do with why it was shared. 2) comments that are critical when opinions weren't asked for

Write that down, you socially clueless assholes.

*Someone posts a photo* "Look at my dog doing this funny thing!"

Assholes:

"Wow, you really need to clean your ____."

"You have weird fingers."

"Is that you in the reflection? Put on some normal clothes, it's 2 pm."