It might seem like an anomaly to say that sin can have a smell. I must be the only one who thinks this but I can smell hatred, I can smell what is rotten. I can see what decays and is not sustaining of good morals. That is not to say I am the center of all morality, Jesus is that, but I can detect rotten fruit from good fruit.
You realize, don’t you, that I am not speaking of the physical and mental universes, which I use my reason, my senses, my environment to tell what smells, what looks evil, what feels bad. I speak of smelling in the spiritual universe (physical, mental and spiritual universes). If all of us can smell what is evil, see what is evil, and know what it is, why do we humans keep making fools out of ourselves in the name of freedom of choice.
Some people can smell evil, some cannot. Have you had the exprerience of smelling a rotten potato in a bag. Gag! If we seek to love God with all our hearts, all our minds, and all our strength and our neighbor as ourself, then what is not that smells, sometimes just a whiff and sometimes downright repulsive. You know the sayings from Scripture that point to something not being quite right.
John 15 New Revised Standard Version Catholic Edition (NRSVCE)
Jesus the True Vine
15 “I am the true vine, and my Father is the vinegrower. 2 He removes every branch in me that bears no fruit. Every branch that bears fruit he prunes[a] to make it bear more fruit. 3 You have already been cleansed[b] by the word that I have spoken to you.