Search content only

How do I search only content and ignore matches in the filename?

I know I have this article about webarchives, but it’s a bit hard to find…

A smart folder that excludes filename matches suppresses results when the content matches as well.

I tried Spotlight, but at least with the Finder interface it’s no good either.

That’s not currently possible with indexed searches. You could perhaps write an AppleScript that searches the “contents” property of each record. The “contents” is a plain text version of what would be displayed in the viewer; it excludes the filename, title, etc. This would be relatively slow, however, as accessing the “contents” requires rendering each Web page, PDF, etc.