MH->Netfabb is giving my models smallpox

[sweatpea]

When I add models to netfabb to get them ready for 3d printing, the smooth surfaces get messed up.

So far I have found netfabb to be the best software for fixing errors and simplifying geometries if it wasnt for the introduction of the messed up surfaces.

I have tried cleaning them first in blender, meshlab and meshmixer and I get the same result.
I have have also tried exporting as obj instread of stl with the same result.

Does anyone know how to prepare the models for netfabb cleaning.
I have one which is a mix of facebuilder, MH and a blender pose which Icant get t oprint without a serious acne.