I've been known to run out of patience trying to get all the old glue off carbons and just fletched over the residue. I think on the shafts that have a matte surface finish like Gold Tips, the glue soaks into the surface a little, so the glue actually becomes part of the surface layer. You'd actually have to remove some of the original surface to get all the glue off. The shafts with a fine surface finish, like Beman, don't allow the glue to soak in. Bottom line, just get the glue line scraped/sanded down flush with the shaft surface and fletch. They'll stick.