Is it possible for boys cats to pffft a smelly pissy smell despite being castrated?

[ripstheirthroatoutliveupstairs]

I don't have a terribly good sense of smell at the best of times and have a cold at the moment.
I think I can smell a sort of old uriney smell in our house. We do have two kittens, both are around 24 weeks old and doctored.
The do still have little balls, but no testicles apparently.
Help.

Not sure about kittens but my adult boy (also neutered) still sprays when something upsets him (like a new smell) or marking territory.

It's not a nice smell at all and the amount of times I've spent on my hands and knees sniffing out his latest patch so I can clean and treat it...

Pets at home sell a very good spray that I use which is very (simple solutions stain and odour remover) no scrubbing involved and makes the area smell acceptable to the human nose again immediately.

My old boy was neutered as a kitten but still urinated around the house on occasion and it smelt a lot. Not as much as a whole tom by a long stretch but certainly smelly enough.

Yes it is, I often see my female cat squirting up the fence panels in the garden. I understand its a marking territory thing, so males tend to do it more often than females.

Try a feliway diffuser here

Spraying is usually stress related, this helps reduce spraying.

Do you have 3 litter trays around the house(one per cat and one extra) and total access to outside via catflap?

They don't have a litter tray any more and I am loathe to reintroduce one. They have unfettered access to the outside world too.
Neither look stressed, they do fight with each other but play fighting rather than no holds barred stuff.
DD can't smell it so it's probably my post stop smoking nose playing up.

Maybe something outside is scaring them or one of them?