Characterizing and understanding carbon nanotube (CNT)-based polymer composites plays a crucial role for the ability to customize their properties. The (an)isotropy of CNT networks inside a composite can have significant effects on the final material's properties. However, characterizing the (an)isotropy of seemingly random CNT networks can be difficult using standard techniques. In this letter, we show that terahertz polarization sensitive measurements can provide a reliable, noninvasive and fast way of identifying anisotropy in seemingly homogenous CNT networks as based on criteria by standard techniques.