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
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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.