To me, the successful photo has a poetic flow to it. This flow can be one of harmony or one of discord. Whatever it is…the photo flows. This poetic flow is what separates the snapshot from the photograph. It is the same with the successful poem vs. a mass of meaningless words. One has poetic flow, the other does not. The poetic flow makes it stick in our mind.
Sometimes the situation does not allow for much poetic flow. You just want to record that moment in time.
That is how I think of poetry as it relates to photography.