Actually, looking at an image upside down is a good way of discovering if your composition is good. In the past artists used to turn their canvass upside down in order to see if their composition 'worked'.
Originally Posted by Mohsen al-Dajani
It works because it helps to remove context and it's better if you can 'defocus your eyes a little - if you can't identify the subject, you see the relative positions of the tonal areas in the image more clearly.
As a previous poster said, 'embrace the upside down image, it's your friend.