I’ve been meaning to revisit my WordPress 404 Errors for Spam Comments but somehow it kept slipping through the cracks. I was at a bit of a loose end so I did a quick run through my spam comment log and my site’s error logs…
There were 424 spam comments to my site in December 2010. Of those 74 had an associated 404 error for the comment page that WordPress would have made had the comment been approved. All the comments and 404 errors that paired had IP addresses that matched. I’d say that suggests that the spambots are checking if they succeeded to get a comment posted rather than someone auditing to check the inbound links they’ve paid for exist.
The test for a comment page that causes the 404 error isn’t happening immediately so the bots have been coded to allow for comments being delayed. I can’t think of a reason a comment would be delayed other than moderation. Most of the comments are so blatantly spam that I can’t see most of them being approved. I did a quick sample of the ones I looked at the ones with long lists of links weren’t tested to see if they got through and the random garbage text with a couple of links were sometimes tested.
The most heavily checked spam comments were short like “A very interesting post thanks for writing it!” or “Thanks For the exelent info. I’ll be back in the future. Thanks again! [Link to drugs spam site]”. Maybe a few of the short ones like the second one might slip past someone who’s taken the drugs from the site linked to? I imagine some like the first one will get through on a high traffic blog with lots of comments to moderate.