when water gets bacteria and mold in it, then it is bad.

Damp substrates are hard to keep clean, so a whole tank with damp substrate can cause problems with infections.

Your snake will probably actually make use of damp hides however.

Many of us use a high humidity hide, especially around shedding time, since snakes often make extensive use of humid hides.

By limiting the humidity to a small area, it is easier to keep everything clean. The substrate in the humid hide can be changed frequently and the hide itself can be kept scrupulously clean.

Trying to maintain an entire tank at high humidity is very difficult and should generally be avoided unless the species needs that high humidity (ie BRB).

I live on the shore of a Lake and my cages seldom fall much below 70% humidity and often run as high as 85%. My snakes have no problems as long as the substrate in the cage does not have excessive moisture, and as long as the water in water dishes is changed often.

I never let any water stand on the substrate, and I inspect for defecant daily. When defecant is found the substrate is replaced and the entire cage cleaned with hydrogen peroxide, followed by distilled water, followed by a thorough drying with paper towel.

I have small tupperware bowls with snapping lids that I put my snakes in while cleaning their cages. I spend about 20 minutes cleaning a cage.

David