From reader BlondeMom:

I have the same inserts and you cannot scrub the walls because it scratches them and they lose that shiny finish. I got a real inexpensive cleaner at KMart (called "The Works" and if I remember correctly it has a white label with green lettering); it was cheap (approx $2) and cleaned better than any of the big name brands. My girlfriend and former neighbor just suggested a product called "Greased Lightning." It comes in a white spray bottle and cleans everything, leaves it shiny and smelling good! Hope these suggestions help!