I've seen vast numbers of posts become unfindable by search, and then weeks or months later become findable again.
I think this is an effect of the way Google searches/indices things; I am equally frustrated by pages that disappear from Google's web search which may or may not come back eventually (although I've seen more disappear than come back...) Remember that they're running a huge distributed system, and so consistency/completeness is probably relaxed in order to optimise other things they believe are more important. It's the same reason why even if Google says there are X results in a search, you often cannot view them all.
(Not that I'm actually agreeing with this behaviour, however. It's less noticed on the web where there tends to be a lot of redundant/similar information, but still not desirable at all.)
I think this is an effect of the way Google searches/indices things; I am equally frustrated by pages that disappear from Google's web search which may or may not come back eventually (although I've seen more disappear than come back...) Remember that they're running a huge distributed system, and so consistency/completeness is probably relaxed in order to optimise other things they believe are more important. It's the same reason why even if Google says there are X results in a search, you often cannot view them all.
(Not that I'm actually agreeing with this behaviour, however. It's less noticed on the web where there tends to be a lot of redundant/similar information, but still not desirable at all.)