Degradation of shock absorbers is often difficult to detect due to constantly changing driving conditions. The rule of thumb is that after two sets of tires have worn out, stock shock absorbers are only half as efficient as they were originally and need to be replaced.
You won't get an accurate idea of their condition with a known «swing method» in a stationary vehicle, in which you press the machine over the wheel to be checked and suddenly release it: the movement of the spring must be extinguished immediately. In this way, only a completely faulty shock absorber can be determined.
A more accurate view of the shock absorber condition is given by a special test stand, such as, for example, «Shocktester» (shock tester) from God. The damping of oscillations of a pre-swinging car is shown in the form of a diagram.
The shock absorber fluid must not be too cold to check, otherwise an incorrect result will be obtained. Based on the diagram, the condition of the shock absorbers is determined.