###Overlapping faces

My first impression is that you are trying to fix the wrong problem. I suspect that the reason you are using BSurfaces is because you don't know why you are getting scratches. The scratches is a much more interesting problem, and knowing how to fix those will help you in future modelling. 

If I am correct, the 'scratches' as you call them, are the result of overlapping geometry, tightly packed and imprecisely placed polygons, and this results in `z-fighting`. This can be the result of _boolean operations_. It looks like in object mode you can see some of the problem, overlapping edges will appear visible in edit mode (this is always a bad sign). But without better images or a .blend it's difficult to tell.

### BSurfaces hatching


This is perhaps a little too narrow scope for blender.stackexchange but BSurfaces does come with Blender, so perhaps it's OK to answer. 

you need to draw the crosshatch this way.

![enter image description here][1]

![enter image description here][2]

then adding surface is without issue: 

![enter image description here][3]



  [1]: https://i.sstatic.net/wbfZY.png
  [2]: https://i.sstatic.net/ZtHeM.png
  [3]: https://i.sstatic.net/hWfEp.png