I’m sure that everyone with a blog, or other system allowing users to post comments, has received them at some point, the comments that look legit but basically are spam. The spammers sometimes manage to post something that makes some sense to the topic in the blog post, others are as far off as can be.
Common for all these is that the comments in themselves is not the purpose, the linkback put in the field for website on the comment form is. Though occasionally you come across someone that posts an interesting, or otherwise useful link, most of them lead to pages of no interest at all (I for one is definitely not interested in where on the internet I can by certain meds).
To the inexperienced it looks just like any other comment, with an author linking to their website. After a while it becomes rather clear that the posts are essentially spam though, the exact same comment starts showing up with different sites linked.
This is a comment from one of my other blogs:
I’ve recently started a blog, the information you provide on this site has helped me tremendously. Thank you for all of your time & work.
That looks like a rather legit comment, right? Taken out of context it certainly does seem so, but put in context with the subject of the post it was commenting, it is very far off.
That particular comment was found in a blog post containing a recipe for a Sandwich layer cake, on my Wine and Dine blog. I seriously doubt that helped the poster in any way regarding starting a blog…