Re: Should you believe what you read?
One thing to remember about non-fiction is that though it is touted as being completely factual it is also told through the eyes of the writer who has an agenda regarding the subject matter.
For instance: An author who is a democrat and who is writing a non-fiction work about a democratic president will have a very different view on that president than a republican writing a non-fiction work about that same president. One is more likely to focus on the positives of the president's time in office, the other may be more inclined to point out that president's failings.
For instance: A biography written about someone is going to be very different than an autobiography of the same person. One is writing about themselves and could be trying to do damage control on a sullied reputation, could be trying to share the lessons they learned in their life or could be simply hoping to make money. The other is writing about someone else and would be trying to frame them in a certain light to acheive a certain goal. Both books would be "factual" or non-fiction, but neither would be the same nor would they present the facts in exactly the same way.
For instance: An atheist writing about religion is going to have a very different viewpoint and interpretation of the same facts as a theologist writing about religion.
My own interpretation on this subject is that no matter what non-fiction you read, take it with a grain of salt and don't just believe it on face value because it's presented as "fact", especially when it's a subject you're trying to form an opinion on. Read several works by several different authors presenting several different viewpoints and then determine your own interpretation as they will all show the same "fact" in a different light.
"I could have been in politics 'cause I've always been a big spender."