you'd feel the looseness of the car when driven if the bushes have started to fail, plus you'd get the clonks and knocks from the rear when on-off the power that gives an idea on the condition of the A frame bush. Not sure if worn bushes will be heard when stationary considering most are pretty hard to push up and down to judge any movement Most have seen some track use as well so bear that in mind as well. But regardless, for me, I would look, inspect, buy then take it to someone to change all the fluids and give it another once over, that would have saved me a small fortune 3 to 4 years ago.