jdMorgan - 3:26 am on Jun 9, 2010 (gmt 0)
> This new report also gives us a hint that such redirects may not even be doing any good for the target page.
> The only reason I can think of is to try and recapure the link juice.
Although SEO is a valid consideration, at least one of the posters in this thread is talking about the "traffic retention" aspect of 301-redirecting removed pages to the home page.
The purist's answer -- and I believe what Google "wants," is a 404 error page with a 404 HTTP response code.
That 404 page can include many if not all of the elements of the home page, along with a "non-scary" explanation that the requested URL was removed and links to the HTML site map, major category pages, site search page or facility, etc.
The same is true for intentionally-removed resources, which should return 410-gone status, and an error page almost identical to the one described above for 404.
Just make sure that any bad URL returns an HTTP 404 or 410 status directly, with no intervening redirects of any kind (NB: to include domain canonicalization redirects, etc.)
If that requirement is met, the content can be anything you like, and Google will just have to fix the problems at their end (remove their faulty 'heuristics'), unless they actually want to encourage non-HTTP-compliant error handling (which I doubt).