Maintaining the cleanliness of leather gloves can be done dusting them off with a soft cloth or towel.
Other ways of cleaning depend on whether the leather is finished or unfinished. For finished leather you can lightly dampen a cloth, and add a small amount of moisturizing soap to the cloth. Rub it into the leather until the soil has been released. Wipe clean with a clean lightly dampened cloth, and then buff with a dry towel.
For unfinished leather, saddle soap is recommended. Use a damp cloth to apply the saddle soap to the glove into a lather. Wipe it clean with a damp cloth and let it air dry.
To preserve the look of either type of leather, leather conditioners for finished leather and preservatives like Mink oil for unfinished should provide the best result.