Most of them are mostly if not completely circular. The rules also call for imperfect circles, which they are, like most of the others accepted. However, if there were an issue, the rules should not be so grey and left to the interpretation of the artist. They should be clear and concise, but changing that now would cause many of the accepted entries to need editing. When I personally draw these, I stay as circular as the design calls for, without being too perfect. Simply put, I stay within blurry guidelines.