This study presents a novel framework that integrates information quality and the Dunning-Kruger effect to deepen our understanding of affective polarization. Information quality--a degree to which information is capable of yielding knowledge--has been overlooked in political science. The Dunning-Kruger effect suggests that individuals with lower levels of knowledge frequently overestimate their competence, leading to overconfidence and negative attitudes. By examining the implications of low-quality information exposure, this research hypothesizes that such information diet exacerbates the Dunning-Kruger effect. Utilizing the ANES 2020 dataset, the study tests the hypothesis that low information quality diet correlates with reduced levels of political knowledge, increased and strongly held negative political attitudes, and heightened levels of affective polarization. Ultimately, our findings underscore the nuanced ways in which information quality shapes political attitudes and behaviours, providing further insights into the growing divides in contemporary democracies.