It looks like one client did blast a few posts with crap - presumably to increase the juice passed. Withholding link reports doesn't solve things either - people can see the new links quite easily in GWMT.
I've heard a few people say i'm not big enough to be on Google's radar.
I just made a decision never ever to but any links from a forum BST section. For all I know Google's search quality team keep a close watch what's being discussed on SEO / IM forums.