Using it to affect taste and smell is speculation and there are many people who will agree that it does add a bit of a light sweetness to the buds, i'd even be geared more towards saying this is true as i've noticed a slight difference in grows i used molasses in. But the real reason that people use molasses in their grows is because it "feeds the soil" the natural sugars in the molasses break down the nutrients in your soil to a level that the microbes and healthy bacteria in the soil can consume which lets your plants uptake these nutrients much easier