For a study, researchers sought to understand that self-identification is still the most common method for recruiting specific clinical subpopulations, which may impact data validity among respondents motivated to feign a condition for financial gain. Online respondents who said they were taking medication for a specific medical condition (sample 1: diabetes, N=307; sample 2: pain, N=506) were asked to upload an image of their medication. These images were then evaluated to identify authentic and inauthentic responders based on the images submitted. The authentic and inauthentic respondent groups were then compared on condition-specific health and attention tests. Respondents whose photos were deemed inauthentic passed fewer attention tests and reported poorer physical (e.g., number of comorbidities) and mental health (e.g., diabetes distress) across a wide range of measures in the diabetes sample (η2=0.014–0.159). In the pain sample, respondents whose photos were deemed inauthentic reported worse physical (e.g., pain interference) and mental health (e.g., depression) across a wide range of measures (η2=0.008–0.129). The findings suggested that online survey respondents who feign health conditions such as diabetes and chronic pain may significantly exaggerate their adverse health outcomes. As a result, in the absence of procedures to verify health status claims, data validity from online survey respondents should be regarded with caution.