I don't fully understand this. How did you look at your link profile? Is this a blessed google thing ? And how do you know your drop in rankings is down to this back link issue - what if other people have written better stuff (apologies !)
There are several tools out there which scan your backlink profile and give you a report on your backlinks. They usually scan the sites and give you a "danger" rating for those sites. I can't remember the name of the tool I used but I had nearly 20K links in the "danger" rating. Half of them were super-spammy sites that simply repost what you already posted, the other half was a mix of bloggers (good and bad).
Usually you can tell that it's because of that issue when a major penguin update goes out, and your rank suddenly drops. To confirm it, you'd disavow the bad links (so, the link farms that link back to you, the reposters, reblogers, spammy affiliate sites etc.) and see how it affects your ranking and exposure.
It worked VERY well for me once everything was said and done.
