I think with more and more research being done strictly online, teaching students how to discern a trustworthy website from an untrustworthy one is essential. Even more so, students need to be able to navigate the different agendas and biases that are an unavoidable reality. A good video I like to have students watch is the Wolfgram Memorial Library's Evaluate Web Pages Video, which gives a great overview of the criteria for evaluating web page credibility:
I think it's a tough pill to swallow that (almost) everyone is selling something even if you happen to agree with him or her, but as teachers, I think we ought to try to encourage that kind of disinterested critical thinking anyway.
Have a good weekend, and good luck out there!