What is one sign of worn wheel bearings?

The correct choice highlights that grease residue on the trailer or boat is a sign of worn wheel bearings. Wheel bearings are essential for enabling the smooth rotation of a wheel, and when they begin to wear out, they can start to leak lubrication, which is typically grease. This grease can escape and leave residue on the trailer or surrounding areas, indicating that maintenance is necessary.

Seeing grease residue suggests that the bearings are no longer functioning properly, potentially causing inadequate lubrication and leading to further issues, such as overheating and failure. Regular inspection of wheel bearings is crucial for maintaining towing safety and performance.

The other options do not indicate worn wheel bearings. Excessive fuel consumption does not relate directly to the condition of wheel bearings, as it's more indicative of engine or efficiency issues. No noise when the wheel rotates could actually suggest that the bearings are functioning correctly, as worn bearings often produce noise. Bright colored stains could indicate a range of issues, including fluid leaks from other components, but they are not specifically associated with the condition of wheel bearings.