Currently, I am not a judge of photographic competitions.
After 2 years of entering competitions, I have often wondered what exactly do Judges look for, and what criteria do they apply when marking an image?
Fortunately, The Scottish Photographic Federation (SPF) has published information on this very subject. On their web page, in the paragraph, Booking Forms and Guidance Notes (about 2/3rds down the page), there are a number of downloadable PDF documents. One of which is entitled, SPF Judging Guidance Notes 1 - What Judges should be looking For.
Reading the points so listed has answered my initial questions, and it may give an insight to others as to what points are considered during the Judging process.