I have one "special" cat. Fisher, my Burmese does thing thing of his I call "jealousy marking". He uses the litterboxes, but when he perceives that he might be getting less attention than my alpha cat Siete, he will pee in Siete's favorite spots to mark them as "his". Not complete bladder empties, just enough to smell. I am a pretty fastidious person, and my place rarely smells of any pet odors. But when Fisher has done his thing, I smell it as soon as I come home from work. I can find the spot pretty easily, and they are invariably places Siete likes to hang out.
I have been using a combination of Nature's Miracle (don't waste your money), and a more expensive enzyme product called Formula 66 from AirX (works well on light markings). Neither one is 100% effective nor do they pass the blacklight test. If you use a blacklight, you can spot urine areas easily. Nature's Miracle might kill the smell, but the stains still show under a blacklight. So...how to pass the blacklight test too?
This Magical formula:
16 0z Hydrogen Peroxide
1 Teaspoon dishwashing liquid
1 Tablespoon Baking Soda
Mix it up in a spray bottle, or pour it on carpets. Once dry, there is no more smell AND it passes the blacklight test. Peroxide will not discolor fabrics or plastics or wood. I got this recipe online, after being frustrated that I could get a whiff of cat pee on my microfiber couch where I watch TV. Turns out Fisher peed right between the place where the back cushion of the couch meets the bottom cushion. The back has foam beneath the microfiber, and the bottom has memory foam. The place where they meet is a place you can stick your hand all the way into and hit the back of the couch. The cushions are not removable, so I could not really get to everything, especially not the foam.
I lifted the area (like spreading butt cheeks!), and sprayed this solution between them enough to make it soaked, And YES! No more smell, even with my nose right in that crack, and no stain AND no blacklight shockers.
Peroxide is cheap as hell. And you really do not have to add the dishwashing soap. Just peroxide alone will do the trick, but the baking soda might enhance the chemical action. If this is a problem you have, you will thank me for posting this later!