Think about something you know a lot about, i.e. something you have a bit of expertise in. How do you know when someone you're talking to about this topic knows what he or she is talking about?
How is your judgment different when you're hearing someone talk about something you don't know much about?
From the Joyner Library, East Carolina University http://media.lib.ecu.edu/reference/howdoi/display.cfm?id=42.0
Use the following 5 questions when evaluating the information provided
by a Web page to determine its credibility:
1. Who Created the Web Page?
2. When Did They Create it?
3. Why Did They Create it?
4. What Perspective does it Represent?
5. Is the Information Reliable?