When He shed His perfect blood for us at the cross, the Lamb, our Saviour Jesus Christ paid for our sins once and for all. But that does not mean we do not grieve the Holy Spirit when we sin. In Psalm 51, David cries out to God after he realizes the evil of his transgressions of adultery and murder, and through his sorrow and pain, we see how merciful our Lord is when He is faced with a heart of true confession.
A clean house, a clean car, clean clothes, even the proverbial 'clean slate' - why do we so enjoy things that are clean? Perhaps...