I've judged many quilt and embroidery shows. Each judge comes with their own likes and dislikes, but when we've had discussion on picking a winner in a specific category, the judging has been impartial and only on specifics: quilting quality, color choices, choice of design that fits the fabric designs. binding application, quality of applique, etc.
Here are several things to NOT do and how to correct them.
Rippling edges. Measure the width and length along the center of the quilt. This measurement could be 2 inches shorter than the edges. Work the excess in when binding. Do not just start sewing a strip of binding and go the to other end. Guaranteed--your binding edges will ripple. Quilts should be square. A beautiful white on white hand quilted piece lost best of show because of a rippling binding. Later after my job was done, I was told by a quilt member who knew the quilter that she ran out of time. I insisted that it wasn't the winner and the other judges finally agreed.
DON"T bring in a piece that has animal hair on it. One time, I had a quilt that must have been a cat's bed while under construction. UGH! I put it aside and made a note on the entry card that "I don't judge cat hair." I looked at the quiltmakers name after I eliminated it and discovered to my total surprise that it was someone in the quilt world who should have known better.
Hope this helps. SandyQuilter