Interesting people will post a picture and tell you something about the context in the caption.  "Here we are at (blank) park during the trip we took and here are some interesting things that happened that you can't see on camera but are interesting and you might want to hear about." Fats take pictures in which they take up 80% of the photo and there is nothing interesting to say about it because taking the photo was probably the only time they got up from eating a 10 course "picnic".