In a reasonably well-functioning society, most people have few opportunities to profit from doing something really bad; it almost certainly wouldn’t be worth your while to kill somebody even if you had nothing in your ideology or in your character to prevent you from doing so.  This means that for most people in such societies the negative experiences that they will have had at the hands of others will have been comparatively minor: inattentiveness, insensitivity, manipulativeness, glory-hogging, and so on.  Since strong negative emotions tend to be about bad hings that people have actually experienced, these evils will tend to be the most salient, and so be the ones that people are most on the lookout for when making judgments about others.

This can be a serious bias when the person you are trying to judge is likely to have an opportunity to benefit from doing something really bad.  This is the case in some personal relationships like marriage or business partnership, but the obvious example is politics; politicians have enormous scope to abuse their power, and this fact attracts people who would like to do so, so there is a decent chance that a candidate for high political office, especially a chief executive, is a serious bad apple, even if the proportion of bad apples in the pool from which politicians are drawn is low (which I daresay it often isn’t).  So among the most important signals that people should be looking for in a political candidate is whether they are keen to abuse power.  That may be hard to do even in the best of circumstances, but it’s made harder by the fact that people don’t have a separate character-judging template that they trot out special for judging politicians; they just use the template that they use in everyday life, which is good for things like figuring out which co-worker might try to take credit for your work on a project (and so might serve to screen out a candidate who is a relatively harmless glory-hog), but which is terrible for things like figuring who might decide to go around promiscuously killing people (and so might serve to let through a candidate who is a monster).