[bitwize]

Before Google, unscrupulous web sites would try to SEO themselves into the top page of search results with repeated META tag bombs or sometimes just good old fashioned whitefonting. One of the innovations of PageRank was that more widely linked-to web sites would be ranked as more authoritative, doing an end run around the kind of keyword spam that plagued the early web. If the most widely linked-to web sites wish to play ball with SEO marketroids, that undermines the trustworthiness that PageRank assumes for those sites.

The upshot of this is that no system is impossible to game.