I'm not a quilt show judge but i do judge quilts/clothing at the jr. fair level. When we judge clothing we look at the construction-is the method used appropriate for the type of fabric. We look at the type of fabric-is it the type recommended for that type of garment. are the seams finished properly?does it hang properly?
As far as the quilted items, again we look at the construction-are the seams holding or are they coming undone? If it is hand quilted-are the stitches even? For machine quilting, lines evenly spaced if doing a crosshatch, FMQ-are there eyelashes? Are the corners mitered? if so are they even or sloppy? If it finished "envelope style"-are the front and back even? Or does it look crooked and twisted when it's layed out?
We also consider the overall look. A pillow that is carefully done will outplace a large quilt that looks thrown together.