1. The scented clay based cat litter.
I had tried a lot of sand litters from unscented to scented and from the cheapest to the expensive one. As for now I prefer to use the scented clay sand litter with clumping effect from fussie cat product that comes with 5 types of scent litter (lemon,peach, rose, apple and jasmine). The clump effect can make the scooping work easier while the scent aids in reducing the odor.
p/s: I hate crystal litter because they only managed to absorb the urine but not the smell...sucks!!
2. Scoop the waste material at regular basis.
Even if you use the best cat litter but you still too lazy to scoop out the cat's waste then you will still face the same problem of the bad smell.
3. Food type.
Wet food makes the cat's feces smell bad than the dry food. Some dry foods are formulate particularly to reduce the feces smell. I use the blackwood super premium cat food which give my cats' feces less smelly.
ok...say if you have done all the step above but the bad smell still stings your nose!!!!! Now i surmise you might find a perfume, air freshener, essential oil bla..bla..bla...
Believe me none of those scents work well, they do not eliminate the bad smell rather just covering it for a certain period of time.
I highly recommend you to use the charcoal room deodorizer from Farcent
This product contains binko charcoal with natural plant extract which can absorbs the bad smell effectively. You can placed the deodorized next to the litter box. I brought it from Giant store not sure whether other large store does sell this too. So..check your nearest Giant Store now!!! (chewah dah mcm Giant promoter plak gwe haha)