hi, I was always taught to sing from the heart and only to sing songs which grabbed me, unfortunately this makes me very intolerant of those that either:-
A cant be bothered to learn the song

B sing the song as if reading it from a book without inflection or emotion

C lokk as though they would rather be cleaning up after the dog!

D cant remember the tune or stay on key

As to what judges look for goid knows - i rarely agree with the songwriting competition winners at festivals and when eveyone sings a different song at singing competitions it must pretty difficult to be subjective givenm the possible influence of material choice etc