I think it depends if you bombed the correct target, then the mission should be considered a success. If you bombed some other target of opportunity then it is a fail. Some missions require you to destroy more than one structure for the mission to be successful. I would say the mission is success no matter what the CO says, as long you or your flight hit something in the target area (as shown in the debrief screen). Just like arty spotting - there is no way to tell if the mission was a success. To me it is successful if you got to the target waypoint, loitered for the requested amount of time and returned home, or at least landed on your side of the mud.

"Take the cylinder out of my kidneys,
The connecting rod out of my brain, my brain,
From out of my arse take the camshaft,
And assemble the engine again."