I look for photos that show guys who have been circumcised. It must be clear that they are circumcised. I reject most photos where it is impossible to verify. I have noticed that many uncut boys are photographed with their foreskins retracted. Most of the time this can be detected. I look for the folds of skin behind the glans and the shiny head. A circumcised penis often has a discernible scar which can be seen in even the worst photos.
The other thing I look for are guys who are in shape. No out of shape guys here.