Auto-spammers

I'm fascinated by little software engines that generate blog spam automatically.  They often do a pretty good job saying something generic and not totally out of line with the rest of the content.  For example, during the holidays, a spam appeared here with the message "Thanks, super site!".  Humor me, I like to think this is a super site.   Such statements are not entirely irrelevant so they are not entirely spam.  It's like junk mail: it is not junk if you are going to use the $15 discount card Macy's sends you but it is junk if you are not interested.

Well, an even more confusing case is this other message, which said:

I said the same thing about the tree ring chart; I guess I'm paying attention. ;)

The comment links to a blog that looks authentic but there does not appear to be a post that deals with the tree ring chart.  So I'm all confused.   Is this the work of an ultra-smart auto-spammer or a real person?