When I say clean I mean Shiny bright, like new clean. The Grill stone will clean it to shiny bright clean, however it must essentially sand down the stainless steel bars, which I think will eventually wear down the grills, and as other have mentioned, causes food to stick.
I have been just using a Weber brass brush and it cleans the grills very well, only thing is the grills still remain discolored and dark looking, however food does not stick, so it seems thats the way it has to be.
They sear beautifully, with no sticking, just don't look as purdy as new.