Critical thinking does not come naturally to humans. It requires ongoing training and self-discipline. The difference between the skilled critical thinker and the average thinker is as dramatic as the difference between the physique of a pro body builder and the average physique.
Teach's Precepts for Critical Thinking:
1. High levels of certainly often correlates to low levels of critical thinking 
Examples from the Left and the Right of failure to critically evaluate the issue:
1. On the Left: "All of my friends at the health food store say that immunizations are dangerous and cause autism. There are scientific studies that prove it. Immunizations are part of a conspiracy generated by the medical industrial complex."
In truth, there was a single flawed study linking immunization to autism. The results have not been replicated, and overwhelming scientific evidence supporting the need for immunization reflects the consensus of the scientific community. So, if you believe that immunizations are bad, this belief is likely based on anecdotes, your need to conform to the group with whom you identify, and on your intuitive feelings of paranoia.
2. On the Right: "The guys on Talk Radio say that climate change is a myth. Many scientists agree. The whole global warming thing is a conspiracy perpetrated by liberal scientists who want grant money."
Actually, there has never been a more researched natural phenomenon in history than climate change. Overwhelming scientific evidence supports the validity of climate change caused by human activity and this view is supported by a consensus of the scientific community. If you believe that climate change is not occurring or that it is not caused by human activity, this belief is likely based on anecdotes, your need to conform to the group with whom you identify, and on your intuitive feelings of paranoia. http://www.pnas.org/content/107/27/12107.short
That said, alternative theories to the scientific consensus are a VERY good thing. On occasion, the scientist who opposes the consensus will find strong opposing evidence. As opposing evidence accumulates and eventually outweighs supporting evidence, the scientific consensus will shift to the new position. So, if and when evidence opposing immunization and opposing climate change theory accumulates to the tipping point, good critical thinkers (like the scientific community) will shift to the new position.
I was once trying to teach a particularly difficult theory to a class. About half the class understood the theory and the other half didn't get it. When polled, 100% of the students who understood the theory said they agreed with the theory while 100% of those who failed to understand the theory described it as "stupid." It takes time and effort to become informed on complex issues and no effort at all to have a gut level response. Ironically, the informed individual is more likely to be uncertain about his/her position than is the uninformed individual.
2. Objective evidence and logic outweigh popular views and intuition
3. "Feelings" are not evidence. "Common Sense" is not evidence. "Faith" is not evidence. "How I was raised" is not evidence. "Anecdotes" are not evidence.
4. Changing positions when opposing evidence outweighs supporting evidence is the hallmark for critical thought.
5. Ego is the greatest obstacle to critical thought.
 "Critical Thinking and Emotional Intelligence." Critical Thinking and Emotional Intelligence. N.p., n.d. Web. 29 Sept. 2015.