Is there such a thing as contemporary "goth writer"?

Your personal appearance and fashion choices should have no bearing whatsoever on the sale of your book. And I don't believe any reputable publisher would be at all concerned about that. Furthermore, if they DID raise such a concern, without any research or data to back it up, I'd say they were just looking for an excuse to turn down your book. And publishers don't need any excuses. They flat out reject books---even without reading them---all the time. They don't choose the books they publish based on what the author looks like.