If you see stains or discoloration on stainless steel don't be surprised. All it promised was to stain less and not rust. It does not promise non-staining steel. It does stain, no matter what you do.
I have found the best way to keep stainless steel clean is with a white nylon scrub sponge and a little ammonia solution. This should keep stainless steel looking as good as new. If it becomes dull or stained rub in one direction with a Cape Cod® Metal Polishing Cloth and wipe dry to finish shine.