Once we know the userís query, we can often find alternative text from a page that better explains why that result is relevant. Using this alternative text as a title helps the user, and it also can help your site.
Or, then again, contrariwise, it can hurt your site.
If I, as a user, see the real title I can deduce that the snippet is taken out of context and the page as a whole is about something else entirely. If I see a g###-manufactured title intended to justify their search results, and go to the page based on that title, I'll come away remembering it as a useless and misleading page. If I remember it at all.
And if I, as the site designer, also can't see the search terms (?q= ...and that was all she wrote) I'll never know why someone came to the page and promptly left. Maybe it wasn't a stupid user. ("Why on earth would they think the page is about that?") Maybe the search engine deliberately gave them a mistaken idea of what the page is about.
G### does seem to like my meta descriptions, though. Cross your fingers and hope they don't start rewriting those.