I was trying to clean some label goo off of a calculator display recently, and "Goo Gone" wasn't doing it alone, while I was afraid to use a fingernail.
I ended up retrieving a used fabric softener sheet from a laundry basket. After most of the aromatics have been boiled away, the softener sheets' substrate is like a loose, random nylon (or ???) mesh, with a very slightly abrasive quality.
Along with Goo Gone, it worked like a charm, and it was free. ("Free", that is, if someone near you uses fabric softener sheets in the dryer.)
FWIW