My cats have always made me suspect they understand plain English. And they do things that convince me that they have their own reasons for whatever they do–reasons which will always be inaccessible to humans.
The closer we look, the more personality we can see in animals–especially our pets. After all, they live intimately with us and some of us is bound to rub off on them. A jolly home makes for a jolly dog. I can’t remember who said that, but it’s true.