I seem to remember that there is a magic doormat revered on Mumsnet for its ability to just suck the filth from the shoes of anyone even just standing briefly on it. But I can't remember the name of it. The combination of new sunroom floor tiles which somehow show every mark, and an elderly labrador who plods in and out all day, is driving me insane. So what is this wonderful thing? What is the name of it, where can I get it, is in hugely expensive, is it worth it?