My email accounts attract a lot of spam. Fortuntely, running the incoming through SpamAssassin takes care of most of it. Accordingly, I don’t get the “opportunity” to read much of it. I also have a strong interest in effective writing for which the small book “Elements of Style” by Strunk and White. Andrew Sullivan provides this link to writing guidelines for authors of spam in the spirit of Strunk and White.
Elements of Spam