According to the Ontario Real Estate Association,
"Mould is composed of microscopic organisms that can cause health problems, when present in large quantities (colonies) within a structure. Mould thrives on humidity and reproduces by way of spores that travel on air currents.
Moulds are most commonly found in damp locations, e.g., kitchens, bathrooms and leaky basements. Tell tale signs include staining, visible mould growth (which may be only the surface of a much larger problem) and musty smells. Often, mould growth is not readily seen as such problems go unnoticed behind finished wall surfaces.
Mould can also be found in attics. Without proper ventilation, warm air will condense leaving moisture behind which will likely result in mould. Mould can have an adverse affect not just on air quality but on structural components in a building.
Mould is everywhere and it is unrealistic to think that a home would be mould free. Mould spores have certain requirements including moisture, air, a temperature in the range of 40 to 140 degrees Fahrenheit and a food source which could be anything from drywall to plywood. Mould is controlled by controlling the amount of moisture in a home. Without the life sustaining environment, mould will go dormant only to reappear when conditions are right.
Aside from health issues, mould can contribute to structural damage in buildings. Mould eats cellulose found in wood and in the worst case scenario can affect the structural integrity of the wood. Mould today is not such a big issue as most insurance companies have built in exclusions for damage caused by or resulting from mould. This is due to a previous history of massive claims in the United States. "
Note the phrase, "large quantities". The problem we've encountered in the industry is who is qualified to evaluate large quantities. I suggest that home inspectors with the odd exception are NOT.
