In some cases, I would have to say the thing that really makes a photo great.. is the viewer. Some people love some of my worst pictures because it has some sort of sentimental value. When a person looks at a photo, they bring their life time of experience with them and all that experience has subconscious impact. They might pick the picture with the old hound on the porch even though everything about it is inferior to the next guy. Maybe they grew up with a hound just like that and it had emotional connection.