In general leather is mostly affected by moisture and dust and need lot of care which can not be done if in use..you cannt keep it closed atmosphere too..However there is a solution for it. Leather bags can be cleaned with a special conditioners designed especially for it , which is available is market or the leather stores and even furniture shops. If you can not find it just use some very mild soap water of Dove. However after cleaning you have to wip and drain it thoughly...use hair dyer for that.