Comment spam is getting more intelligent

Recently a reader remarked that one of the many sites that pretend to be a blog, but in reality just copy content from other blogs to get hits for their advertising, used a new technology: They ran my content through a program which replaced half of the words with the help of a thesaurus, so that it looked like completely different content. Now I noticed the same technology being applied to comment spam: The spammers take real comments from various blogs, run them through a thesaurus program to make them appear new, and then post them to another blog. At first those comments look a bit strange, but legit, until you notice the link at the bottom to some gold-selling or advertising site. As I said in my Terms of Service, you can link to your blog, but you can't link to a commercial site. I'm deleting this new form of comment spam, as I've always deleted the old-fashioned kind. But the advances in technology even for spam are interesting.