In 1992, when Bill Clinton was running for President he was stung by allegations of infidelity. In response, his defenders made the argument that "character doesn't count".
His presidency showed just how wrong this was.
Around the time of Clinton's impeachment, some of his defenders argued that it didn't matter what he did on the side, because what was most important was having the most effective person in charge.
The problem with this argument is that if someone doesn't have character, how can you count on that person acting in your interest rather than his own?
Different people enter into politics for different reasons. Some sincerely want to do good. Others are only interested in promoting themselves.
Of course, people who want to do good can nonetheless do great harm. And self-interested people may do the right thing for the wrong reason. But people who enter politics only for themselves usually end up doing harm.
Sincere activists are willing to work with others. They readily advance the fortunes of others who share their values, since this aids the causes that they care about.
Self-interested politicians seek more power for themselves. They manipulate people to their own advantage. They seek to damage rivals for positions of power. They pursue a "rule or ruin" strategy to destroy organizations that they cannot control. This hurts whatever causes they claim to care about.
Such people use underhanded tactics and dirty tricks to get ahead. The influential book The Road to Serfdom by Friedrich Hayek contains a chapter entitled Why the Worst Get on Top. Hayek explains that bad people get ahead in politics by using tactics that good people shun. Good people often get fed up and leave politics because of such behavior.
How can we tell the sincere from the self-interested? A good indicator is their personal behavior. Those who are sincerely interested in helping people should act this out in their personal lives. Those who are only interested in themselves should exhibit this in their personal lives as well. Those who exhibit immoral and self-destructive behavior in their personal lives can be expected to do the same in politics.
Interestingly, the sincere seem to be much more likely to be religious than the self-interested. This shouldn't be surprising, since those who believe that they will be held accountable for their actions are much more likely to behave honorably in both politics and life.
People who wish to do good in politics would do well to beware of political climbers and resist their efforts to do harm.