graeme_p - 9:50 am on Sep 1, 2013 (gmt 0)
The spammy SEOs current sales pitch is that you need nofollowed links to make your link profile look natural to Google.
Nofollow has failed. The way to deal with spammy comments is to remove them.
Google would have been better off either developing auto detection of spammy comments further, or penalising sites that fail to remove spam (surely failing to remove spam is an indicator of low quality?).