According to Osho, to be without stain means your original nature is utterly pure, untouched by desire, thought, sin, or guilt. Nothing needs cleansing or improvement; only the illusion of dust must fall away. Awakening is not polishing the mind-mirror but recognizing there is no dust, no mirror to clean—your intrinsic innocence is already complete.
You were born perfectly clean inside, so stop trying to scrub yourself; just notice your natural goodness.