Link farming, probably. If you have a network of scraper sites already, you inject links to the posts into other posts. That's one of the motivations behind com

Link farming, probably. If you have a network of scraper sites already, you inject links to the posts into other posts. That's one of the motivations behind comment spam as well: it builds links pointing to a site, whether people look at the spam or not. I don't know how much Ye Olde PageRank still factors into Google results, but I'm assuming it's still a significant factor.