It would be even better if Admins have an option to mark a profile unsafe. That way, they won't have to worry that a user will mark their images as "safe" in the future and the owner of the websites gets penalized by Google Adsense or similar ad network which do not allow NSFW images. If a user is recognized as regular NSFW uploader, his profile should be marked as such and it can't be overridden by the user, as all his images will be automatically served as NSFW images regardless of whether or not he mark his images as NSFW during upload.