Geometry:
No isolated vertices
No coincident vertices
No coincident/coplanar faces
Correct face normals
No empty objects
Topology:
Quads and Triangles only
Model can be cleanly subdividable
Other:
(Model file includes only the 3D model)
Model Scale: real-world scale
Model after 'reset xForm'
Model centered at origin (0,0,0)
all objects are named and logically grouped