2. Self-critical
There are a lot of people who try to boost their egos by ignoring their flaws. No matter what they do, they will tell themselves that they were right and they are the best at it. But smart people are quite the opposite. They are quite critical of themselves. They will bring out every little flaw they have and analyze it. They will try to get rid of their flaws and try to achieve perfection. For this reason, they tend to be the most honest people.