Any physical description of the Mary Sue main character beyond a very short, offhand, and in-context phrase.

The sentence, "I hope you have as much fun reading this as I did writing it" in the cover letter.

You know there's a problem when . . .

You're judging a sonnet contest and run into a 22-line poem with one end-rhyme, archaic diction and barbaric syntax . . . and it's one of ten by the same author who actually thought enough of his work to pay the reading fee . . . which is somewhere in a landfill with the rest of the reading fee checks . . .

Your assistant editors injure themselves to avoid slushing through contest entries. And the reading fee, though small, isn't worth the time it took you to read the first ten words - so you seriously consider returning all the reading fees as they are inconsequential.

 . . . your contest entries are all 'promising' to the point that you're ready to invent (yet another) alter-ego to announce as the contest winner and spend the prize money on booze enough to keep the judges buzzed enough to keep reading - and the money for the next issue on sponges and a steam-vacuum to clean up all the vomit.