..The only point that's going to get across to her is that you don't want her peeing. She will not associate your yelling at her with her peeing on the tin foil. In fact, really the only way to communicate with a cat is to let them do it, or speak to them in their own language. Yelling means nothing to them. If you must, hiss at her. And you still may want to consider using potting soil in her litter box, and the rocks in the potted plant are an awesome idea.
Just remember..cats are smart. They often have very good reasons for doing what they do, even if it bypasses our logical reasoning. If you want her to listen to you, you need to speak her language. I've told my parents over a thousand times that yelling at a cat to stop a behavior means nothing to them. All it means is that their human is making loud noises. I'm still technically new to cats myself, and I've learned this. Well, cats seem to respond to hissing(psssst! or tssss!) and stepping towards them threateningly. 'Course....even that's not always enough and some cats I've done that to just hold my gaze. Some cats you need to hiss at and literally chase them away from the object. It's kinda like how dogs will respond to short, firm commands, because to them, it's like a bark, or pronouncing their name slowly in a low, warning voice - because it sounds like a growl.
Last edited by FlickeringHope; 01-27-2011 at 01:03 PM.