Permanent ghosting is part of the game if you print wb black. I have my staff check with a loupe for mesh blockage if in doubt. 99.999% of the time it's just stained under the mesh knuckles and not impeding. But yes, we do have ghosting that has to be tolerated. It's all fairly soft but it's there.
Not tolerated: mesh blockage, holes of any size in image area, any ink whatsoever on the frame, excessive tape left on frame.