As the webmaster for the Vintage BMW Motorcycle Owners club, I have to watch over the site and keep it looking good. There are a couple places on the site that allow anonymous commenting, and they attract the spammers.
Because I'm using a slightly offbeat CAPTCHA, I've never had a spambot be able to post, which is really excellent.
But CAPTCHAs just determine who's a human and who's a 'bot. Real human spammers can still post. So, I have to watch over them and remove the spam when I see it. Drupal does a pretty good job of selecting which comments to put into a queue for me to approve, so it's not too heavy a job to delete all the crap.
Until recently, the spammers would try to post innocuous items with text that was phrased in a supportive way but didn't actually say anything, and then they would drop in their link somewhere. I guess the idea was that a harried moderator wouldn't notice that it was content free. An improvement to this technique was not putting the spam link into the body of the comment, but instead supplying it as the website of the poster, which Drupal would kindly convert into a link around the poster's "name". That was a nice, subtle touch.
Today, however, I had a comment waiting for approval with actual relevant content (and the poster's name as a link to some unrelated website). I know the content was relevant, becaue I wrote it myself! Pretty clever! The spammer just grabbed a paragraph from the original post and added a little bit of text to it. A quick skim might have passed it.
I continue to be impressed with their ingenuity.