I've managed to get rid of black dots by:
- Exporting an affected item from Sweet Home 3d in OBJ format
- Importing the OBJ file in Blender
- Exporting it (without a change) from Blender as Wavefront (obj) file
- Importing this "obj" file as new Furniture in Sweet Home 3d
This worked well for Advanced photo but some dots were still present when shaders (Phong and Uber) were applied.
The car on left is original (downloaded from Google 3d Warehouse), the car on right is AFTER the export/import trick.
