We present qualitative monitoring of multilayered films by noninvasive investigation in the terahertz frequencies. Three multilayered films composed of marine paint are characterized in reflective, non-orthogonal measurements in ambient atmosphere. The spectra of the constituent marine paint layers EH2350, Interthane 989, BEA777, and ENA300 present sufficient spectral information for effective monitoring of the multilayered structures. Our experimental findings show promise in noninvasive monitoring of layered structures in realistic industrial evaluation applications.