I have 5 cats, 3 female, 2 male, ALL desexed, ages ranging from 8-10 years.
I have an issue with a cat (or more?) spraying in strange places. One common place is on the kettle. None are allowed on the bench. The other place is on the curtains hanging behind the freezer. I often find spray on the loo paper in the bathroom. I understand that it is/can be an anxiety and territorial thing. As the curtains overlook the neighbours places the 'other cats' could well be the cause of that place being targeted. But the kettle? And a plastic bag?
In addition to the spraying, someone likes to pee on the freezer. It's a proper pee, not spray run off and is usually done on papers of some sort. The other favourite place is the bathroom mat.
The cats are indoor/outdoor cats and go to the loo outside, so litter box issues don't seem to be applicable.
I've cleaned all the areas with vinegar and or bi carb to discourage this, but it doesn't work. Sprinkling white pepper does, but not for long.