 You start getting that moldy, mildewy smell. Now it's time for awesome. You just drop a half a teaspoon of awesome right into your empty washer, run it on a full load with no clothes, but like a large load of hot water. Might have to run it a couple times the first time you use it. Rinse it, drain it. Now you've got a washing machine that doesn't necessarily smell like lemons or flowers, but it's just clean. And that's what the goal is.