Bhagavad Gita, Chapter 18, Verse 31

That which has a distorted apprehension of Dharma and its opposite and also of right action and its opposite, that intellect, O Pârtha, is Râjasika.

Real confusion is named here specifically, not knowing right from wrong even when trying to tell the difference.

Krishna doesn't describe this intellect as simply less sharp, he names a genuine failure to discern rather than a lack of effort. Real confusion, not laziness, is the actual problem.