Pre-election opinion polls are an increasingly prominent aspect of political campaigns, yet they often vary in terms of their results, sources, and where they are published. Citizens are therefore increasingly confronted with the proposition of which polls to give more credence to than others in shaping their voting behaviour. This study investigates the relationship between subjective determinations of poll credibility and voting behaviour in the polarised context of Turkish mayoral elections. The theoretical perspective of motivated reasoning is employed to consider how individuals determine and act upon credible opinion polls in mixed information environments. Using an original two-step experimental approach conducted in 2020, this paper establishes that while the effects of opinion poll credibility on party choice are limited to the strategic considerations of the supporters of smaller parties, opinion polls can have considerable demobilising effects when polling environments are conflicting or deemed not credible. The findings produced in this study are more suggestive of accuracy-seeking than directional motivations, and they have considerable implications for how we think about the relationship between polls, politicians, and voters.