One site I have been involved with is a database of research findings on a particular academic topic. The database is poorly constructed, and consist of the same title tag for all 5,000+ findings
Site: Research Finding
and no description tag
Needless to say, the site's traffic has been poor for the last few years (they didn't have a budget to rework the entire database).
So I am surprised that Google now totally overwrites title and description tags -- on a consistent basis. Google is not picking up random terms within the page, but picking specific fields in the database and uses them for the title tag and description tag. The 5,000 findings that this site has now uses the title tag
Site: [Title of the study where the finding came from]
Description Tag: One sentence entry blurb summarizing the finding
I am just amazed that they do this consistently for all the 5,000 findings of this database.