Abstract: In computational electromagnetics, the discontinuous Galerkin method is a widely adopted and effective approach for handling non-conformal meshes, offering significant flexibility in addressing challenges posed by complex geometries. Historically, the integral equation discontinuous Galerkin (IEDG) method required additional stabilization terms. increasing algorithmic complexity. Recently, a simplified discontinuous Galerkin (SDG) method has emerged that eliminates the need for stabilization terms while effectively processing non-conformal meshes and maintaining high computational accuracy. This study systematically classifies flawed non-conformal meshes encountered in non-conformal discretization scenarios. We further investigate the inherent mechanisms through which the SDG method processes various types of flawed non-conformal meshes, evaluate the impact of mesh imperfections on computational results, and comprehensively discuss SDG performance across varying mesh conditions, providing a reference for non-conformal grid modeling and electromagnetic scattering accuracy assessment of complex engineering targets.