aristotle - 9:56 pm on Jan 13, 2012 (gmt 0)
Tedster - it's hard to give meaningful examples without revealing the names of a couple of my websites, which I don't want to do even if it were allowed under the forum rules. But there is a pattern - Specifically, if I have an article with a title of three words or less, Google will often append the title of the site's home page to get its SERPs title. For example, if the home page title is "All about Widgets", and the article page title is "Antique Widgets", then Google will use "Antique Widgets -- All about Widgets" as its generated title for the article page.
But that example doesn't really show the extent of the problem, because for my two affected sites the home page title sometimes doesn't "fit" the subject of the article very well, with the result that Google's generated title looks odd and illogical.
What especially annoys me is that Google makes this change even when my page title exactly matches the search term. So if someone searches for "Antique Widgets" and I have an article called "Antique Widgets", Google still changes it anyway.