When they start using the strawberry bed as toilet, where there isn't even any dirt, and, because there's no dirt, they can't/don't bother covering it, I draw the line.
I have been THOROUGHLY dusting any area used as toilet (actually, I've only found 3 spots in the front yard, but 3 is too much!
) with a mixture of cayenne pepper and wasabi powder. Any cat that has returned to sniff around went home with streaming eyes, nose, and what my DH calls the "Wasabi Hit".
If their owners don't care enough to keep them safe at home, then I cannot be held responsible and will take what means are necessary to keep my garden clean.
As I have said before, if dog owners are required to pick up dog poop, cat owners should be responsible for cat poop as well.
(I have two indoor cats who get supervised outside time in our garden and no dogs)