The Qur’an states:

{وَ اتَّقُواْ اللَّهَ  وَ يُعَلِّمُكُمُ الله}

Be God wary and God will teach you.  Only when one is God wary can the true realities can be learnt .([1])

“Taqwa”, God Wary, means to distance oneself from bad and ugly actions.  So yes, people who have a polluted heart are prevented from seeing many of the realities.

If one is a fanatic about their culture, tribal connections, sectarianism, race etc.… they cannot understand realities, just like one who is wearing red tinted glasses in which everything they see will be tinted red, they will see turnips as beet.  Likewise, one wearing green tinted glasses will see hay as green grass.

If a mirror is polished, it will reflect perfectly what is in front of it.  The mirror of the heart also needs to be polished in order to be able to reflect and understand realities.  A heart with a grudge is like a dirty bowl, in which if clean water is poured in to it, the water too becomes polluted.  Sins are like the dirt and dust that does not allow mankind to see realities and truths.

[1] Baqarah 2:282