Using a humid hide does not mean the snake should be sitting in water: whether you're using soaked sphagnum moss, orchid bark or sponges, etc- you want enough moisture contained in the hide to raise the humidity, but you're right, with the warmth + humidity, it would tend to foster bacterial infections if the snake was actually "sitting" in water. You want the hide to start out "very damp" but no visible "water level"- and then you check every couple of days to add moisture as needed, either by spraying or re-soaking & draining out the excess. The moss holds a lot of water in it after a soak, but it also provides air spaces too, so the snake is never actually sitting in water. I've never seen a snake get skin problems when this is done right. But good question!