In a reconstruction procedure based on the iterative solution of inverse scattering integral equations, the quality of the final image depends on both the numerical and experimental noise. Numerical noise is related to the accuracy of the numerical representation of the microwave imaging apparatus and system geometry. Experimental noise refers to the nonideal electromagnetic conditions in which the data acquisition is performed. This paper provides a systematic evaluation of the impact of the most significant sources of numerical and experimental noise on the reconstruction quality when the Iterative Multiscaling Approach (IMSA) is used. The assessment of the robustness and stability of the IMSA is carried out by considering synthetic as well as real data. The achieved results provide detailed indications on the range of applicability of the IMSA for qualitative and/or quantitative imaging purposes.