Well, having a mother who got terribly ill and was bedridden for almost a year because of some cat taking a sh*t in our garden and thus spreading some disease the night before my mum went gardening, I can understand this lady wanted to get rid of this cat.
Though of course in the end it's not the fault of the cat, just of the owner. If you think it's cruel to keep your cat in your own garden/house, don't take cats. It's much crueler to ruin somebody's life by letting your cat sh*t in their garden.
Yes, I hate cats. No, I don't put them in the bin. The most I do is scare them away if one comes too close.