tedster - 7:33 pm on Jan 13, 2012 (gmt 0)
I appreciated the second, more detailed page that this article linked to. The two together can make a good reference to send to clients.
Here's a good example of the kind of retail that rang the bell for me:
For larger database-driven sites, like product aggregators, hand-written descriptions can be impossible. In the latter case, however, programmatic generation of the descriptions can be appropriate and are encouraged. Good descriptions are human-readable and diverse, as we talked about in the first point above. The page-specific data we mentioned in the second point is a good candidate for programmatic generation. Keep in mind that meta descriptions comprised of long strings of keywords don't give users a clear idea of the page's content, and are less likely to be displayed in place of a regular snippet.