I recently just checked my Google webmaster tools and noticed a bunch of links that I didn't recognize. When I downloaded the sample and visited the pages, I noticed that they were the same spammy links with the same anchor built to my site over and over again... words cannot describe how angry this makes me. I've done nothing but keep the site as clean as possible and build only acceptable, branded links on social profiles and other media to help grow its presence.
I don't want to disavow them because I believe disavowing puts the site under some type of microscope where your site experiences even more zombie traffic. I've noticed this difference on penguin hit sites vs non penguin. I'm not sure, but I don't want to risk it at the moment.
Some people say that it's impossible to spam a competitor, but somebody knows what they are doing here. Building exact match anchors will get the site penalized.