wondering about spam

I use Akismet, and as a result most of the spam directed towards my blog gets trapped. Some stuff does get through, and there’s something about the stuff that gets through that intrigues me. So I thought I’d share it and find out if anyone can shed light on the phenomenon.

A large percentage of the spam that does get through seems to be directed at a particular post, as shown below:

It’s an old post, nearly three years old. And it doesn’t read too well, the quotation marks have been replaced by hieroglyphics ever since I recovered the post from backup. But I can’t see anything unusual or different about the post, something strange that would attract spam. Yet maybe 70 per cent of the spam that makes it past Akismet is directed towards this post. Anyone know why? Anyone experience anything similar?