Bad Shading on Imported Mesh I have imported a mesh (AutoCad DXF) and I'm experiencing strange shading behavior. I've done the following to try and address the problem with no luck:

Recalculate Normals
Remove Doubles
Delete Loose Geometry
Cleared Seam, Sharp, and Bevel Weights

There are no modifiers on the mesh.

The original imported mesh looks fine in smooth shading but I need the mesh to be in quads which causes the shading to mess up as shown in photo. I can add my .blend file but I'm not sure how to do that.
This is generally caused by custom normal data.

Under the Properties Window > Object Data > Geometry Data press Clear Custom Split Normals to get rid of it.