I agree with Martinibuster here, whatever we do to try to please Penguin at this point is nothing more than a best guess shot in the dark and the fact we're trying is more information for the search engines to use at their discretion. Right now I rate the disavow tool as "probably can't help" and "might further harm rankings". I used it on one site and saw absolutely no effect in terms of rank/traffic.
Fact: Google claims that you should remove incoming "bad links" to reverse Penguin effects but under the same breath claims that someone else can't sink your rankings by giving you bad links. Both can't be true, proceed with caution.