1 Reasons
- If the object is warped or disorted, the lighting is not proper, then the parallax occlusion doesn't work or some normals are missing:
- The import settings are wrong.
- The export settings in Blender are wrong.
- Within Blender there are objects with a global scale.
- If there is a texture missing, or a face may has no texture:
- Some faces may have no texture, but they should have.
- There exists a material which shouldn't be there.
2 Solutions
2.1 Import settings
Content Tool options: "Import filter for x3d filters" has to be the correct value.
2.2 Export settings in Blender aren't correct
They have to look like this: 
2.3 Objects are scaled
Every object has its own coordinate system. This coordinate system can has a translation or a rotation without causing problems. In Blender you can scale the object, but the Content Tool doesn't like that at all.
You can check the object settings (hover the mouse above the 3d viewport and press [N)] within the "Transform" section.
To apply the scalling just go within the object mode to "Object" ==> "Apply" ==> "Scale".
2.4 Some polygons have no texture
Well you have to search this polygone manually. 
2.5 There is a material with no connection to a polygone
To delete this material every object should be treated like written below:
- Select the object
- Go to the properties window (by default on the right side) and choose the squared ball (Material)
- Just below this card there is the material list. This list has by default only one material with the name "Material". All materials in this list has to be deleted by clicking on the minus symbol next to the material list.
