Its a loosing battle with the dust bunnies, you just have to stay after them. The longer you wait, the more you get. I use a "can of air" on mine, the reloads, and my holster every couple of days if I think of it. My gun usually gets shot once a week so it gets cleaned anyway.
I've always used an IWB holster and used to have a major problem with rust. I sweat like a pig and Im active, both at work and play, and leather holsters with blued or parked guns are a bad combo, especially in the warm and sweaty months. In that case, hard chrome or Tennifer and kydex are your friends.
Kydex holsters in general are just much easier to deal with too. The dont absorb or hold moisture, nor do they release irritating chemicals. They dont generally embed dirt or abrasives, and can easily be cleaned by rinsing them out under the tap, and instantly ready for use, by drying them with a paper towel.
They also dont wear the guns finish "overall" like leather. They do wear on the specific contact points though, which can mean noticeable wear marks in a few places, but the rest of the gun looks new.
Kydex is easier on your body, and doesnt rub you raw like leather, and especially wet leather, when its against your bare skin.
Price wise, they are usually a lot cheaper, and last a lot longer.
at a time. 
