Douse the house with unpretentious wine.
Get an Indian girl to come over, cook for a couple of days while you have your ways with her. Wine and dine her if you must.

I feel for you YJ - first, get a BLACK LIGHT and go around the house in the dark. The black light will make cats urine (even old, dried stuff) glow.

Second, there are various products - Odoban, for instance - that are enzyme-based, that are meant to attack to source of the smell, rather than mask the smell. You buy it in a concentrate and then soak down the areas. It may now smell of chemical for a bit, but that will go away -- open windows, insert fans...

Third, if you cat is not using a box, even when clean, it may be indication of a urinary tract infection, and possibly worthy of a vet check, and subsequent change in food. Or it could be behavioral - we have had cats where a change in household routine resulted in peeing in random spots because they were pissed off - so is there something in the household that is perhaps upsetting the animal?

Get a squirt gun -- when you see cat in bad places, squirt them.

Get "Bitter Apple" spray - cats hate the smell and avoid the area - so if they are consistently going someplace - say behind the bookshelf - to pee, spray liberally with biter apple to keep them away from that place.

Hope these are helpful. Good luck!!

1 the "day to day" running of the household is the Housekeeper's duty & that person reports to the "Mistress" of the House, or your good self if you are a Bachelor.

so delegate the specific tasks to a cleaning person, and use your scone, ----
--- plenty of fresh air,
cleaning generally, so the place smells of disinfectant, beeswax timber polish etc
"cat litter trays" cleaned & new "cat litter".

I should ask what the F**** are you doing owning domesticated pet cats ?

You are a MAN (alledgedly), you should only have "cat litter" for the purpose of soaking up oil stains from your motorbikes & / or motor vehicles from the concrete

Only Gay men have domesticated pet cats.

Proper Christian Heterosexual MEN may keep Tigers, Leopards, Cheetahs, Pumas,
Lions if they are going to "keep cats"

No wonder a lot of you younger chaps are "going to the dogs" ( or cats )

if you are a Bachelor you place should smell of Old Leather (furniture), Gun Oil,
Cigars & Whisky, with a whiff of Expensive Tart's perfume

"I intend to clean" -- arghhh ---you are GAY
You uncivilised blighter, you "intend to get a cleaning person in" !!!!!!

Do NOT Listen to Zultar,
Crikey a combined stink of Cat Urine & Curry is the sure way to disinheritance

& seriously --get rid of the cats ( unless your rich & cultured Aunt is daffy about cats )

Cats live in unfinished basements and outdoors. The only non-caged animals that belong in the living areas of a house are man's best friend, the dog.

zultar are you indian?

you need to have your Aunt believe that you are capable of & intending to provide her with nephews & nieces who will be raised as christians and educated properly at the correct private skools, once you have married a young woman of whom your Aunt approves.
Lament on the dificulty of finding a suitable spouse & Aunty's response will tell you all you need to know. If Aunty has any serious interest in you, then she will seek to select your future spouse.
If she dismisses out of hand the notion of you marrying & siring offspring then you're
not even a contender in Aunty's schemes or for a share of her estate.

Is this Aunt a Spinster with no family of her own ? Or does she have her own offspring to inherit her estate ?

I thought the only "non caged" or "aquarium'd" creatures to be let indoors
were Women, Children & the Domestic Staff ( as well as friends & relatives )

Domestic staff aren't animals (they aren't that high in the food chain), I have no kids or they would be caged kept, and I keep my wife in a pit in the backyard.

ROFL you guys are hilarious. I think my question is answered.

My cats are using the litterbox well, I've never caught them going anywhere else, so I think it's really just a strong animal smell, not so much a pee smell - though it might be worth checking out.

If one of your cats is male it *will* be peeing (spraying) over things to mark its territory, whether there's a cat tray or not. My daughter's cat even peed in my crash helmet! There was no way to get rid of the smell, I had to buy a new one.

STA neutered males don't do that generally unless something is wrong, usually if they feel threatened or stressed or their litterbox isn't clean.

Snip your cat.

I really don't like litter boxes so my cats are always indoor/outdoor or just outdoor. If I forget to put the cat out before going to bed, it is my fault when he stands on my chest and shoves his face in mine to wake me up in the middle of the night.

Wish that was an option, Ald. Apartment living :(

You can get litter-boxes that are enclosed and have a cat-flap...