>> Apparently supplementals are not always suppplementals? <<
Correct. For URLs that are marked as Supplemental and which return a "200 OK" status, the current content of the page will be indexed and appear as a normal result, while any searches based on older versions of the page will appear as a Supplemental Result. The supplemental result allows searchers to find content that they looked at recently but which is no longer on that page.
>> These are mostly all 302 pages. <<
There is almost no valid reason to be using 302 redirects these days. I would look very carefully at your site architecture before you hit any snags.
>> Of these 444, about half of them are printable version pages which last year we had told Googlebot not to index (via robots.txt).
Yes. Using robots.txt to keep duplicates out of the index is a very good idea. I just fixed a 50 000 page site that was exposing 750 000 URLs in just this manner: [webmasterworld.com...]
>> After the recent changes in the algo, I figured I'd reopen them (trying anything here). <<
If by "re-open" you mean "show them to Google", then that would be a very big mistake. Google takes a year to drop a Supplemental Result from the index when it represents a page that is now 404, redirects, or is excluded from indexing after it has been indexed. Exclude those URLs again, and make that permanent.
>> The other half are pages which were for paid listings which are now expired. We redirect them to another page until they're paid again. I'm thinking this probably isn't the best idea. <<
Make sure that the redirect is a 301 redirect (not ever a 302 redirect), OR make sure that those URLs take you to a custom 404 page (one that realy does return a 404 HTTP status code) that has basic site navigation on it to get the visitor headed in the right direction.
>> I just tried the supplemental search and came up with only 6 pages that really are supplemental. I guess all I can do now is to ignore them. <<
YES! If the Supplemental Result is for a URL that is now a 301 redirect or is now returning a 404 error, then you can safely ignore that result. Google will drop it from view after one year. You cannot control that action. In the meantime the 301 redirect, or your custom 404 page should be feeding the visitor through to the correct part of your site anyway.
If the supplemental result is for a URL that still returns "200 OK", then that indicates a problem: usually duplicate content of some sort (URLs with multiple different parameters that show the same content, www vs. non-www, multiple domains, http vs. https, etc) or pseudo-duplicate content (multiple pages with same title and/or meta description, or page content that is too similar).
>> With Google, it takes a perfectly unique page of content, with unique title, etc, and makes it supplemental. Then, they show up as non supplemental for a few days, and then go back to supplemental. <<
Supplemental, or not, depends on the search query for live pages, those that return "200 OK".
Additionally, it depends on the datacentre. If you look at gfe-gv and then at gfe-eh you will see big differences. The data at gfe-eh has had a big change made to supplemental results a few weeks ago. That change is now also on many other datacentres, but is still far from being on all.
See also: [webmasterworld.com...]
[edited by: g1smd at 12:47 pm (utc) on Sep. 12, 2006]