There are at least 2 of the neighbours cats who keep pooing on a gravelled area in my garden. Every day there's 5 or 6 pools of foul diarrhea for me to clear away before my lo can play out, and I'm losing a trowel full of gravel for each one! I'm really fed up! I've tried "Get Off" gel crystals and a similar spray, they didn't work, there was cat crap there the very next morning.
So I'm considering getting a sonic cat scarer but they're about £20 - do they work?