aristotle - 1:40 pm on May 19, 2012 (gmt 0)
If the backlinks to your site are just being devalued, you won't gain any rankings improvement by having them removed, even if they are part of an "unnatural" backlink profile. So the question is whether the unnatural profile is causing a penalty. That possibility opens a big can of worms, such as whether it gives a competitor an opportunity to harm you. So at this point, I don't think anyone outside Google knows for sure what actions you should take.