Aspiration does not trigger the protective cough response in some patients. The patient’s response may vary according to fluid viscosities and volume. The authors of this prospective study investigated the prevalence of aspiration and response to aspiration of different viscosities and volumes of fluids in patients referred for flexible endoscopic evaluation of swallowing (FEES). Patients with stroke and other neurological conditions were recruited for the study. The study found that the incidence of aspiration with thin fluids was 32% and with thick fluids was 18%. Higher prevalence of aspiration was noticed with thick fluids compared to thin fluids. Some patients responded variably to different fluid volumes and viscosities. The authors suggest that, due to the inconsistent cough response of patients to aspiration, patients cannot be labelled as ‘silent’ or ‘overt’ aspirators based on bedside swallow. Instead, all patients should undergo instrumental swallowing assessment (FEES) to plan fluid viscosity and volume management.