While any keyword filtering regime can be exploited, as apparent by the SEO cottage industry enabled by Google Pagerank, et al, I still find the underlying question unresolved of whether such filtering is ultimately useful to would-be employers.

That is, are employers wanting appropriately skilled candidates, or are they wanting individuals who happen to exceptionally savvy to the flavor of 'SEO' used by headhunters? One can't assume these groups will always overlap.