> I think that this is exactly what is happening. The 'optimizers' have determined
> by trial and error what makes good rankings and they are worsening the S/N ratio
> vs. sites which do not try to climb artificially. Either that or the 'linked to'
> metric has stopped being relevant. In any case, there seems to be a cutoff, like
> a cache size or similar, that prevents certain sites from appearing in listings
> at all if their rankings are low.


That goes back at least to the wars between the pro and anti
scientology folks in the early 90's.  Scientology created bunches of
"spamsites" that all linked to each other and nowhere else, and was
actively hacking at the search engine's selection criteria.
Google was involved at one point.
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