The gild takes on an antique patina when distressed. It can be used for some some soft edged designs or cross-hatching or just simply cutting back on the visual strength of a solid reflective area.
Several methods all work. Steel wool works well, especially if you want a linear scratch, as it tends to look scratched with fine lines.
A more general non-scratched finish is to lightly rub water-gilded leaf with a damp sponge in the same way you normally use to remove excess leaf from around a design. If you stop halfway, leaving some gold, the result is a pleasant antique finish. Red or brown makes a great backing color for 23ct gold (shown on left).
Distressing and scratching of oil-gilded leaf tends to really kill off the lustre. Instead of a velvety matt finish, it can look dull, however every finish can be useful somewhere. It can also tear pieces of oil-size off the glass leaving small holes. On the lower left is oil-gilded 18ct green gold.
On the right is water-gilded aluminium, rubbed with whiting on a damp cloth and backed with black.