fathom - 4:04 pm on Jun 2, 2013 (gmt 0)
I have some thats more than 10 years old, checked the backlinks in WMT and have some recognized as backlinks, some were discovered in 2006, but some wasnt until 2011, before google just ignored them.
Should I disawow them?
Actually Google didn't "just ignore them"... all links were applied to your link graph so if you had links that were unfairly acquired they unfairly provided link juice to drive up your ranks and Google simply ignored the fact that you unfairly acquired those in the past.
But they always maintained that such link violated their TOS.
Disavowing implies you wish to drop it from the link graph so it does not pass PageRank.
That is the same as having the site owner add a rel="nofollow" attribute to the link element and that is also the effect that PENGUIN does automatically for you.
If one is already done the "dropping from the link graph" the others will have no effect.
So if you have any links that have been downgraded by PENGUIN they have already been disavowed by PENGUIN and you don't need to worry about them anymore.
You can certainly delete, or edit with rel="nofollow" or disavow them - but what confirmation did you get that Google took action against "that particular link?" ... or will take action against that link in the future?
In my experience if such a link wasn't devalued by Google's PENGUIN all you are doing is destroying your ranks even more.
Just because you don't like it (that particular link) does not imply Google hates it to.