I recently started a petition to stop negative SEO. We are all waiting for penguin update. We know Google will unleash it very soon. We want to make sure any future update to Penguin algorithm should take care of possible negative links from competitors. We don’t want to keep looking at our links in webmaster tools and update our disavow file.
https://www.change.org/p/google-inc-stop-negative-seo
Competitor negative SEO