Which factor is not necessarily a sign of pest infestation?

Excessive noise is not necessarily a sign of pest infestation because while it may suggest activity in the environment, it can also come from a variety of other sources unrelated to pests. For instance, the sounds could be due to mechanical equipment, ventilation systems, or even customers and employees in the establishment.

In contrast, unusual odors, customer complaints about pests, and gnaw marks are more direct indicators of pest presence. Unusual odors may indicate decaying pests or things like droppings, which can suggest an infestation. Customer complaints often involve sightings of pests, serving as a clear signal that there may be an infestation that needs to be addressed. Additionally, gnaw marks are physical evidence that certain pests, like rodents, have been in the area, further confirming their presence. Thus, while all signs of pest activity should be taken seriously, excessive noise is not a reliable indicator of an infestation.