Although, we do not have an exact formula for deciding what content is appropriate and what is not, we do use the general US PG-13 rating system as a guide when we are unsure if a drawing passes our PG goal. On drawings we are unsure of, just like the PG system, we use a majority vote and our moderators regularly discuss with one another and review drawings. Quite often we review drawings on a PG scale because we would rather be overly safe than not safe enough, but if you know your drawing would not pass the PG-13 guide, then it will most likely not pass our review.
Below is the PG-13 guide wording from the MPA website to help you decide about reporting content and although it relates to movies, it is a general guide that we also use for filtering drawing content:
A PG-13 rating is a sterner warning by the Rating Board to parents to determine whether their children under age 13 should view the motion picture, as some material might not be suited for them. A PG-13 motion picture may go beyond the PG rating in theme, violence, nudity, sensuality, language, adult activities or other elements, but does not reach the restricted R category. The theme of the motion picture by itself will not result in a rating greater than PG-13, although depictions of activities related to a mature theme may result in a restricted rating for the motion picture. Any drug use will initially require at least a PG-13 rating. More than brief nudity will require at least a PG-13 rating, but such nudity in a PG-13 rated motion picture generally will not be sexually oriented. There may be depictions of violence in a PG-13 movie, but generally not both realistic and extreme or persistent violence. A motion picture’s single use of one of the harsher sexually-derived words, though only as an expletive, initially requires at least a PG-13 rating. More than one such expletive requires an R rating, as must even one of those words used in a sexual context. The Rating Board nevertheless may rate such a motion picture PG-13 if, based on a special vote by a two-thirds majority, the Raters feel that most American parents would believe that a PG-13 rating is appropriate because of the context or manner in which the words are used or because the use of those words in the motion picture is inconspicuous.