Which of the following is not typically considered a sign of mold growth?

Dry air is not typically considered a sign of mold growth because mold requires moisture to thrive. In fact, high humidity levels and damp conditions are usually the primary contributors to mold proliferation. When the air is dry, the lack of moisture makes it difficult for mold spores to survive and grow.

Visible mold colonies, water stains on walls, and musty odors are all indicators of mold presence. Visible colonies directly show that mold is growing, water stains can indicate past or present moisture issues conducive to mold growth, and musty odors often arise from the metabolic byproducts of mold. Therefore, while the other options point to conditions that encourage or signal mold growth, dry air does not support this process.