One of the features I particularly value on WordPress has been the ability to have fairly open comment threads on my blog posts. In the past Askimet used to keep these spam free and people were able to submit comments fairly freely.
Over the course of this year though, comment spam has been getting vaguely more sophisticated. The most common spam has been backlink SEO spam that consists of reasonable emails and pieces of genuine comments mixed with product keywords and generic praise.
This kind of spam seems to be massively problematic to detect. Large numbers of comments have been made to historic posts that presumably have ended up ranking well in Google.
Moderating that stuff has been a chore and if I am away from the internet for any period of time the comment were on the site for a while and this seemed to be encouraging more. I presume the bots are smart enough to detect when their comemnts have not been deleted for more than eight to twelve hours and then they pile in.
The only reasonable way forward seems to me to be switch on someone kind of pre-moderation. I’ve gone for the mildest level of control that seems to work, namely that the first post by a user will now be moderated but once someone has a valid post they will be able to post freely.
As for the creators of these ingenious bots, a decidedly slow handclap; well-played.