"When working in Blender New Users ometimes get confused when they compile their model for game and find that at certain angles Faces disappear or they can see through their models to the background, but it doesn't look that way in Blender.

The reason is that game cameras pick up on the painted outward surfaces of the mesh based on the direction of the face normals and cull out the backfaces. Blender defaults to backface culling is off, and faces are displays both front and backfaces as painted.

Most game engines allow you to add NoCull commands to the materials so both sides are displayed, but are usually set to culling on

There is an checkbox you can select to turn BackFace culling on in Blender and you should toggle this option on and check your painted model for bleeds prior to your final export or render."