According to recent research by Portent, it seems that Google is now likely to penalize sites with as little as 50% suspicious links in their link profiles, whereas it was 80% when Penguin first launched.

http://www.facebook.com/photo.php?f...300808066669.338237.7138936668&type=1&theater

http://www.facebook.com/photo.php?f...300808066669.338237.7138936668&type=1&theater