I've had this problem recently. I can craft a search for something just slightly obscure and specific that should, nonetheless, have had plenty of hits on the "old web", let alone now on the many-times-larger web. But "no pages found". Loosen up the search and it's nothing but Google-friendly blogspam that isn't remotely related to what I'm trying to find. I call bullshit.
Heh, oh yeah, tons of that, usually the ones most relevant to narrowing the search beyond "everything on the Web". Thanks, Google.
So then I do the quotes thing, especially quoting phrases that 100% for sure must exist on some web pages, along with all my other keywords and pretty soon I'm at "no pages found". Pull back just a little, and it's page after page of entirely unrelated-to-what-I-want blogspam.