You can train people to be objective and call things as they really are, but it is hard work and you can succeed only to a certain degree. When their personal interests are involved, it is just next to impossible. Witness how difficult it is for people to admit mistakes here where the only interest involved is saving faces for pseudo-names
This is what is truly great about democracy--Check and balance. The hardcore DPP certainly cannot see the faults in the ex-president Chen and the crimes he committed, but they can see what's wrong with Ms. Li. The hardcore KMT does the opposite.
The hard core people have financial and emotional interests in not seeing these things. However, the vast majority of people in the country don't have these interests and see little personal interest in protecting these people. Democracy lets the hard core people expose the wrongs committed and allows the rest of the society, that has less or no personal stakes in them, to judge.
Of course, it would be nice if the citizenry has a minimal training and education in objectivity, but even if they don't, it is already better than the authoritarian states, especially when it comes to fighting corruptions. I doubt similar things would have even been exposed if they had happened in China.