I seem to remember Brad Roberts (who knows much more than I) commenting awhile back on this topic. He suggested having someone stand behind the car while it is idling and watch the exhaust tips as the driver pulls away. If they deflect quite a bit downward you are due for motor mounts. Hope that helps..........
BTW.....Many years back I replaced my front motor mount with a Pedro's unit, immediate noticeable difference (in a positive way) then with a Box S with ~ 34k miles on it.