That is a fair point lacb, and as a cat owner I am aware of it - my cats don't cover their poo in our own garden and I go scoop it out every few days in places where I don't want it. Having it on your herbs must be a huge pain. I use thorny branches to keep my cats off areas I don't want them on and it works quite well (berberis or firethorn branches work well).

I suppose I assumed my cats don't do it in other gardens, as this is their territory. Perhaps the answer is to have a cat of your own ;-) In all seriousness, though, unless we make all cats into indoor pets (which for many would be cruel) I don't see what we can do as pet owners to address this. Dog owners CAN do something because they are with their pets when they poo. Cat owners aren't.