Lets say you delete product 26 (in the first example) and page 273 (in the second example).  The url's will no longer bring up what google has in the index, but the fact is, the pages products.php / page.asp (as far as google is concerned) still exist.  Google is aware this is databased content... it would know very quickly if products.php or page.asp got deleted but you could be in for a long wait until you see those individual items (referenced by querystring) removed from the indexes.

I relaunched my Webforumz site a while back moving from PHP to ASP.  most of old urls had an .asp extension and a querystring... the actual ASP pages were no longer there (because they're now PHP) and so the results were removed pretty quickly.... however on the old ASP site, we used to have a number of url's like this:  webforumz.com/?id=4, webforumz.com/?id=6 ... now whilst the content isnt there anymore, those url's still work (to google, they exist).... which is why it takes google a long time to remove that content (because it will see them eventually as duplicates of the home page, which they now are).... in fact they were still there last time I checked over 6 months after the switch.

I hope this goes some way to answering your question.

Regards,

Rob