I always watch out for the dogmatic idealogues, the ones without moderation. You can identify them when they say that the welfare of others, often including their lives, should be sacrificed to the idealogue's cause - and of course the others should have no say in it.
Pragmatism and humility are the wisest forms of morality. There should always be something higher than your ideals and goals, either the ideal of other people's lives and welfare, or their self-determination (whether or not you agree with their opinions), or your humility: Unless you are God, you should hesitate to sacrifice others based on your judgement. For me, that's also the philosophical foundation of democracy.