What are the qualities of a good leader? A bad leader?

If possible, research the leadership style of the current school leadership and mention the important character traits to the school. It's important to gauge the level of authoritarianism in the school. Some schools are more egalitarian, while others can have a very top-down, hierarchical culture. Use this information when developing your response and avoid incompatible values.
In general, it's best to avoid mentioning personalities because that differs from leader to leader. Instead, if you want to be diplomatic, focus on what a leader gets done and the kinds of actions they take. Of course, you can always mention the positive traits and actions of leaders you've worked with who have had an impact on you.