What is a sign of a failed shock absorber during inspection?

A sign of a failed shock absorber during inspection is excessive bounciness or instability during a test drive. Shock absorbers are critical for maintaining vehicle stability and control, particularly by dampening the oscillation of the suspension system. When they fail, the vehicle can bounce excessively over bumps and dips, leading to a lack of stability in handling. This condition not only affects ride comfort but also impacts safety, as it can cause the vehicle to lose traction and responsiveness, especially during cornering or emergency maneuvers.

The other choices, while they may indicate different issues with the vehicle, do not specifically relate to the performance of the shock absorbers. Worn-out tires might affect the ride quality and handling, but they are not direct indicators of shock absorber failure. Unusual sounds from the engine can indicate mechanical problems but are unrelated to the suspension system. Lastly, poor visibility through the mirrors pertains to the condition of the mirrors themselves and does not have any connection to the performance of shock absorbers. Thus, observing excessive bounciness during a test drive is a clear and direct sign of shock absorber failure.