Here's one example why both should never be used to judge what is the truth.
This segment is from the Melissa Harris Perry show on MSNBC. The segment involves an eyewitness describing to 911 emergency what a young man is doing with a BBgun in a Walmart store. The most important begins at about 2:05 minutes. His description does not match what this young man was actually doing even though the caller is looking right at the fellow. The caller saw what he wanted to see.
http://www.msnbc.com/melissa-harris-perry/watch/video-released-of-wal-mart-shooting-334558787700
This segment is from the Melissa Harris Perry show on MSNBC. The segment involves an eyewitness describing to 911 emergency what a young man is doing with a BBgun in a Walmart store. The most important begins at about 2:05 minutes. His description does not match what this young man was actually doing even though the caller is looking right at the fellow. The caller saw what he wanted to see.
http://www.msnbc.com/melissa-harris-perry/watch/video-released-of-wal-mart-shooting-334558787700