Best way to test it is by "actual feel" during driving. When shock absorbers go bad, the shaft gets stuck at the bottom and isn't strong enough to retract and push the car back up. Ibig sabihin, kapag nalubak ka, wala ng mag-aabsorb ng impact pababa so yung coil spring at suspension parts ang sasalo ng force. Definitely, mararamdaman mo to sa loob ng cabin.