What visual indicator suggests the presence of pests during an inspection?

The presence of black, greasy-looking marks on walls, pipes, or counters serves as a clear visual indicator of pest activity, specifically from rodents. These marks are often left behind as rodents navigate through an area, and they are typically a result of their fur rubbing against surfaces. Such marks signify areas where pests may be nesting or frequently traveling, indicating potential infestations that should be addressed promptly.

In the context of pest control and food safety, identifying these indicators is crucial for preventing food contamination and ensuring a safe environment. Regular inspections for these signs can help maintain cleanliness and hygiene in food handling areas.

Other options, while potentially indicating issues, do not specifically suggest pest activity as clearly as the black marks do. For instance, clear, recent scratches may indicate wear or damage but don’t typically point to pest presence. High levels of dust or distorted surfaces can suggest neglect or damage but are not direct indicators of pests. Thus, black marks are the strongest visual cue for pest presence during an inspection.