For two years, I had been battling with dark black stains caught in the grainy slip-resistance grooves in the bottom of my shower stall. They were there ever since I moved in and I have tried everything - bleach, scrubbing bubbles, pine-sol, etc. I gave up and accepted them as permanent fixtures in my bathroom. Then I tried scrubbing with these and - they DISAPPEARED! I can't really explain it, but it removed those stains and others around the house in just one or two wipes. If you want to keep your living space clean, these are a household requirement! The only thing is that they do leave a TRACE of soapy substance behind, but it's easily wiped away.