With Google Penguin update it is easy to dominate your competitors not by promoting your own website but it can be done easily by adding a Blog containing spammy back links for your competitor's websites or by submitting their website to directories which has already been punished by Google. This is what we call Negative SEO. Google is more cautious about spammy back links now and it is easy to degrade your competition. I don't think Google have a solution for this uptill now.
After google penguin update, I'm working on 40% of exact keyword match and 60% of using brand name strategies since last 10 days after 10 days I'm chking my keyword ranking, I found my keyword rank more dropped compare than last ranking reports update. plz tel me why?
As of right now you can actually use it for negative SEO, although i find this very unethical. There are even Fiverr gigs for this where people will just blast terrible backlinks to your competitors site and make the anchor text all say the same thing. Hopefully this will be fixed by Google in the near future, but until then we just have to deal with it!