It did not leave marks. I worked at a body shop for years. Here's what you do: use a flat, thin metal putty knife and come in behind the letters. Be careful not to scratch the paint. Put a little pressure and run the knife through the glue. Then you need to use a PLASTIC, flexible putty knife to remove the black glue- tape. You can you also use a rag and your thumb and slowly "roll" the tape/glue off. Then get some OOPS! glue remover and scrub the remaining glue off. This will take some work, but it will come off. Keep the glue wet with the OOPS remover but don't drench the truck in it. Once you get that off, take a little rubbing compound and a DAMP rag. Get some compound on the damp rag and rub the entire area with medium pressure in a circular motion. This will make the color uniform and remove the "stains" that have collected around the bottom of the letters from water and dirt. This will also slightly dull the paint because it's removing an extremely thin layer. Then simply take some good wax and shine it back up again.
I remove the emblems from all of my cars. They look so much better and cleaner.