While Captchas make our comments sections reasonably proofed against automated spam, lately we've had a spate of SEO wankers visiting us. These folks make carefully handcrafted spam, manually posted, that serve only to provide backlinks to their clients' webpages. The idea is that, by sprinkling this URL across many different blogs, they can trick Google et al into thinking that people all over the internet are casually linking to their website. They probably charge at least as much for this per hour as I do in my own consulting job.
I've just modified the text that appears over posts' comment forms to state that folks posting only for SEO reasons are wasting their time, since Zarf or I will delete the URLs from obvious SEO comments as soon as we see them. (We will also delete the comments entirely, if the commenter didn't even try to be on-topic with the related post.)
I manage a small non-profit organization's website and was befuddled by the volume of commentators from Russia who gave a series of non-sequiturs ("I use google"). I feel your pain.
Another good measure to combat this type of spam is to make sure all URLs included in comments have a rel=nofollow attribute set. That way, search engines (the ones that matter, anyway) will ignore the link for ranking purposes.
That may not dissuade all spammers, but at least it ensures they cannot profit from spamming (in case you happen to forget to delete their comments).
Although Word Press makes it comparatively simplified to get up and working with a new blog, they assume you know an awful bunch about blogging. Even looking up to the tutorials at Word Press was trying because they assume you know what the problematic terms mean. How can I determine whether or not to use a trackback if I don’t fully recognize what it entails, what it does, and what the results may be?