We will start off by introducing several concurring epistemic approaches to introspection, as well as the empirical material from the domain, pointing to the basic limitations of introspective evidence. Then, using examples from the philosophy of emotions we will demonstrate that even seemingly adequate use of introspective methods leads to confused results. Finally we will apply this methodological observation to a recent work of Sam Harris concerning the introspection of acts of free will and show that no conclusions on causes and structure of mental states, originating from introspection, can be epistemically secure.