After your cat uses her litter box, the box can start to smell real bad! There are a number of solutions to the problem of cat litter box odor. Spraying an odor remover, (get one with natural scents), around your house is one way. Another is to place a few drops of essential oil in the litter box after you've cleaned it. You can also place a few drops of the same essential oils in the water you use to clean the litter box.
I use a natural litter, which is clay-like and has a number of scents in it already. When it was time to clean the litter box, I added a few drops of clove oil. The best thing to do is keep the litter box clean, and add the essential oils when you're cleaning it out.
We can clean the litter box regularly, but it can still smell bad. One reason is that the litter is not clumping correctly. This leads to more urine mixing with feces, which creates a stinkier situation. We should aim to scoop out all clumps and wet spots after we change the litter once a day or so, and also add fresh litter as needed.
Another reason is that we are using too much litter in the box. If we put too much in there then it won't have time to dry out before we add more and it will lead to an unpleasant aroma in our home.