During a plumbing inspection, what factor might indicate improper ventilation?

Strong odors from the drains during a plumbing inspection can indicate improper ventilation. In a well-ventilated drainage system, airflow is essential to maintain the correct pressure balance and allow gases to escape. When the ventilation is inadequate, it can lead to a buildup of sewer gases, which can result in unpleasant odors making their way into the home. This is often a sign that the vents are blocked, improperly installed, or lack the necessary size to serve the system effectively. Proper ventilation is critical for ensuring that fixtures drain well and that no harmful gases accumulate in living spaces.