In order to cut down on the number of spam comments I have to delete, I went through my blog and turned off the comments on all posts from before January 1 of this year. Despite this, for the past two months, I've still been getting comment spam coming through that I have to mark for deletion.
I first noticed this problem with v2.0.3 and several nights ago updated to v2.1.3 in hopes of getting rid of it. Tonight I noticed comments were still coming in to the moderation queue even though the UI said they were turned off.
To be thorough, I went into mySQL and checked the posts table. Sure enough, the comment_status column for all posts older than 1-1-07 was set to closed.
It appears that just because comments are turned off doesn't mean they won't be accepted. Searching through the support forum history, it appears that this issue goes back at least four months (http://wordpress.org/support/topic/95756).
Is there a way to block spammers from submitting comments on a post that's been marked as not allowing them?