Polls asking respondents about their beliefs in conspiracy theories have become increasingly commonplace. However, researchers have expressed concern about the willingness of respondents to divulge beliefs in conspiracy theories due to the stigmatization of those ideas. We use an experimental design similar to a list experiment to decipher the effect of social desirability bias on survey responses to eight conspiratorial statements. Our study includes 8290 respondents across seven countries, allowing for the examination of social desirability bias across various political and cultural contexts. While the proportion of individuals expressing belief in each statement varies across countries, we observe identical treatment effects: respondents systematically underreport conspiracy beliefs. These findings suggest that conspiracy beliefs may be more prominent than current estimates suggest.