One SSS matrial gives different rendering result.WHY?

[sinfool2012]

I put exactly the same material on my model, and it looks very different in rendering.

No matter how I change the lights or direction of the model, the left leg still looks like a piece of ice

another example: in two circles I used the same material

[aoktar]

Face normal is important. It is reverted when you use symmetry effect.

[sinfool2012]

Thanks a lot aoktar! You saved my day!