In one of your previous columns you suggested using a sharp razor blade to remove adhesive bound appliqués from bathtubs. Perhaps you are not aware of a product called DE-SOLV-IT. This is sold in grocery stores along with the prewash sprays. The label states that it “effectively removes lipstick, make up, blood, scuff marks, contact paper, tape and sticker residue from most surfaces”.
I can only attest to the appliqués on the bottom of the bathtub – it worked like a charm and took less than ten minutes to do the whole tub. A lot less hassle and no possibility of scratching the porcelain finish.