Google is the leader in search for a reason, but that doesn’t mean they’re perfect.

Try as they might, they can’t overcome human ingenuity. Witness this anecdote from BusinessWeek’s Bruce Nussbaum:

And this PR firm is very successful at manipulating search, he said. All the PR firms are successful at creating “independent” blogs and sites that spin out positive news and images about clients.

To the trained eye, spotting a PR-driven blog or website isn’t terribly difficult. But to Google — and to a lot of the people who use it — the difference might not be so clear.

The lesson here? Take it with a grain of salt. Search results, opinions on websites, etc do not have any inherent value. Learning how to suss out credible online sources — and how to disregard PR nonsense — means more today than it ever has before. And it’s going to mean a hell of a lot more in years to come.