I had tons of carts with permanent marker on the plastic. Tried everything and usually alcohol would lighten it... but not get rid of it.

Picked up a pack of Mr. Clean Magic Erasers and put a little alcohol on one... very little elbow grease and BAM it was gone!!

Pair one of these up with Goo Gone and it eats those metallic VOID VOID VOID rental sticker residues up!!

All they are is a slight abbrasive... like super fine sandpaper; but with a sponge so it absorbs it.

Be careful near paper labels though... they rub right off! haha