@Aaa , I ran into this on one of my sits and posted about it here to get advice on how to leave an honest review:
https://forum.trustedhousesitters.com/t/how-to-leave-diplomatic-feedback/
The dogs did not sleep upstairs but the whole house reeked. I happen to be very sensitive to smells and it was so hard getting through this sit that, thankfully, was only for a weekend. My clothes stunk.
In my experience, you have a better chance of not having a smelly house if the dog is non-shedding and I’m not just talking urine, I’m talking doggy smell, in general. I also ask if the dog ever has accidents, where and how often. A question I occasionally ask, although I dread asking it because it’s embarrassing, is, Has anyone ever told you your house smells like a dog lives there? To which, people often answer, “Well, a dog does live here!” LOL Knock wood, I have not run into anything this bad since, although a couple of homes did have a noticeable doggy smell, just not noxious. The dogs in those homes were Jack Russells, Beagles, Labs, Dalmations and German Shepherds. I will still take carefully chosen sits with some of these breeds as they’re fabulous dogs.
As for cats, I also worry about smells from the litter box and if it’s a cat that sometimes misses their aim. I am hesitant about taking sits with more than one cat in a one-bedroom apartment or more than three indoor cats, unless the home is large.