this might sound like an odd question, but, I was grabbing a new Scotch Brite sponge (coarse green on one side, and yellow sponge on the other) from my kitchen and I noticed on the packaging that it says (do not use on stainless appliances, may scratch) Should I be conserned about it putting scratches in my keggle's? I've used them befor, but is there something else I should be using... I figure any scratches are more places for bad stuff to grow....