They can "sag" without being obviously deformed or torn. Your check of the clearance between the transmission and the sub-frame is a pretty good indication the Left and Right (Driver/Passenger) side mounts have "sagged". There should be about 1/2" clearance in there.
An easy way to check the integrity of the "roll-resistors" (Front and Rear mounts) is to: leave the car in Gear/Park (without parking brake on), open the hood, grab one of the front tires and just "rock" the car back and forth while watching the engine. Any significant fore and aft movement of the engine means those mounts are probably in need of replacement.
