I find using the 'verbatim' option under tools is usually necessary to get the exact phrase. However if I also try to use an exact date range (uploaded in past five years, say), then the verbatim option is automatically disabled. Can't do both at the same time, it's really annoying.
>They don't guarantee that the term you quoted will be in the results.
They do guarantee it. Sometimes Google is buggy and messes up in determining what's page is actually visible on the page compared to just being somewhere in the HTML.
That's a loose definition of guarantee, I think. They know what's on the page because they include a brief summary in the results, but even there quoted terms don't always appear.
Here's an example someone posted a few months back where google decided the user didn't really want what they said they wanted: