If her shoe soles were black rubber (it feels like warm tar when hot) then when the pipes are warm you can gently remove it with a cotton cloth and "Goo Be Gone". If the shoe soles were white, or some other color, the residue usually becomes very hard after being baked on to the pipe. Get a high quality chrome polish such as "Turtle Wax Chrome Polish", with no abrasives. Use a 100% cotton cloth to gently massage off the residue, working small dime size sections at a time. If you do it with most other cleaners or cloths it will put scratches in the chrome. Take time to do it right & it will be ok. I learned the hard way.