A thorough investigation of unphysical phenomena occurring in hydrodynamic simulation of deep-submicrometer devices has been performed using 2D numerical simulation on realistic devices. We clearly show that anomalous behaviors exist in all major commercial simulation codes and concern both partially depleted silicon-on-insulator devices (inverse kink effect) and bulk transistors (positive substrate current effect). Since sophisticated solutions, but not yet completely verified, have been recently suggested for enhancing the hydrodynamic model, we propose here a simple and extremely practical solution for assessing the unphysical effects in hydrodynamic simulation of contemporary devices.