Immoral or Incompetent?

In politics there is an age old question about why policymakers, those who implement such policies, and others, commit bad action. The question is, are they acting immorally or with incompetence? I do not usually deal with this question because:

1. It's extremely hard to demonstrate that someone has acted immorally.
2. In politics, my view isn't the only one that matters. So even if I demonstrate that someone has acted immorally under my worldview, it's not always effective at making the person be seen as undesirable.
3. I view both as negative outcomes and I would vote any politician out which did either.
4. Using the view shown in #3, it becomes easy to show desirable and undesirable politicians. I don't have to get into their heads or motivations, I just have to observe the bad action. Because this approach is positive rather than normative, it also becomes easier convince others as well.

That being said, I had a thought on sorting out immorality from incompetence today which I wanted to touch on. It's ironic that the left, who asks us not to judge on moral grounds, is largely the same group which insists that  intelligence isn't a real thing. Did you know that intelligence is extremely difficult to pin down and quantify? Even to define it has been tricky. If intelligence is merely the ability to answer questions correctly then a slow learner can answer some questions better than a quick learner due to prior familiarity with the subject. On the other hand, some learners are quick in one subject and slow in another. Finally, the ability to learn is often determined more by interest than ability. Is the nerd smarter than the jock or are they simply interested in different things? In short, it is unclear whether intelligence defined as a general learning capacity even varies at all, or whether intelligence is a rather constant thing in people and the only variables are interests, experience, etc. Now, consider that competence is dominated by intelligence, but that intelligence can also be seen as mere preference. Competence itself then becomes a matter of preference and the entire dichotomy between immorality and incompetence vanishes because incompetence itself is now also a choice. The only difference is one of direct immorality or indirect immorality, but is there actually a difference?