Google search results haven't been a neutral, accurate reflection of the web for a long time. Whether it's SEO or Google's own algorithm tweaks to favor in-house services, or even Google bombing like "Santorum," Google's search results have a profound power to influence, and as such there exists a powerful incentive to manipulate those results. If those examples weren't enough for you, consider a recent study that shows search results can influence elections.
Psychologist Robert Epstein conducted an experiment with 1800 undecided voters in India, and found that through deliberate manipulation of search returns, he was able to shift votes by over 12%. "It confirms that in a real election, you can really shift voter preferences really dramatically," Epstein told The Washington Post.
This is just another example of why Google should be more public about how its algorithm works. If it can simply be transparent about how information ends up at the top, consumers can make more educated decisions about how to process that information and whether to dig further or even triangulate their search results with several different engines. But at the moment, most consumers tend to rely blindly on Google, assuming it's just serving them the best possible information, even though the search engine remains gameable.