A Suethor is, as the name suggests, an author who writes a story in which the protagonist is a Mary Sue. This person may do it knowingly, unknowingly, or even unwillingly; many times an author seeks not to write a Sue, but doesn't succeed. Presumably a Stu-writer would be a 'Stuthor,' but because 'Suethor' can also be interpreted as 'a writer of Suvian characters,' mostly the blanket term is used. Suethors are people too, and that should be respected. The term is not intended to be an insult. Any Suethor can ask for advice and/or get a Beta reader. Everybody has the potential to improve.