How do I get the room i keep my litterbox in to quit smelling so bad-i clean it 3 times a day and it smells…

I have 2 cats and 2 litter boxes and I use Wal-mart brand kitty litter,scoopable kind.Litter boxes are both covered but not self cleaning.I scoop out their boxes every morning and thats it.I put the used litter in a plastic grocery bag and tie it up before I toss in the garbage and I've become lazy but I empty the boxes completely and soak them in bleach usually once a month.scrub them real good rinse,dry and refill.
The room you keep your litter box in should not smell unless there's a dirty box in it.We have a small house and no one can tell we have a cat let alone 2 until they see them.
I put a good 6 cups of litter in the boxes and add a cup or 2 weekly.When it's getting close to time I scrub out box I stop adding litter until there's barely enough for them to use so I have very little waste.Otherwise I always keep a good 4 inches of litter in each box.
I never had much faith in the self cleaning boxes.
The only time you smell cat boxes here is when my female goes {and trust me it's foul}and then refuses to cover it up.Her payback for our male using the box first.He won't use it till he covers hers.I too have tried switching foods and made the problem worse.
My advice is to get rid of that box and buy a regular one with a hood and a filter and clean it yourself.