I have a large back garden that's all grass and has been a magnet for foxes and cats over the years. Every time I get the mower out I have to walk the garden picking up the fox and cat mess so I don't get it all over my mower, and that doesn't do my stomach much good.
I have tried numerous ways of deterring these pests, I have 2 of the green Pestbye sensors, had them years, but they are as much use as a chocolate fireguard.
I've tried orange peel, spraying lime juice, chopped onion all to no avail. A couple of years ago I bought one of those "ray gun" type thingy's the "Defenders mega sonic scatter cat". Like a gun you point it at the cat on your garden, pull the trigger and it emits an ultra sonic sound at the same time shooting out a laser light basically shows you where your pointing..... ABSOLUTE CR*P!!!
I had it for about a fortnight the only reaction I got from the cats was a look of "What the hell is he doing?" just before they weighed one in, it would have worked better if I had thrown it at them.
The booklet that came with it had testimonials from other users, great, brilliant etc etc. and it said if not satisfied return for full refund. It also said if you send it back it MUST be in it's original packaging and undamaged as they can then re sell it!
They are obviously working on the principal the cats on your garden must be duff cats, so it's obviously the cats fault.
Short of sending for a monthly supply of lion dung {or buying a twelve bore} anyone out there with a foolproof method.