That'* enough of a reason, right there.
The standard method is to push down heavily on the corner of the car so you get the thing to bounce as deeply as you can, then let go at the low point and see how long it keeps bouncing. New struts will minimize the bouncing to the upstroke and maybe just a little bounce down and up following. When they are completely shot, they will give another up down up down up.
Visual inspection may reveal that the hydraulic fluid is leaking out of the struts.
Automatic air shocks may be pumping up all the time or running your battery dead overnight indicating a leak in the hoses or in the air bladder.
Abnormal tire wear can be an indicator for strut replacement.
Noise when you are turning can indicate that the strut bearing plates are going bad.