Identifying illicit behavior in survey research is inherently problematic, since self-reports are untrustworthy. We argue that fraudulent interviewers can, however, be identified through statistical deviance of the distributional parameters of their interviews. We document that a high proportion of the variation in the data is due to the interviewer. In addition, we show that the incidence of interviewer-induced anomalies is strongly associated with the perceived level of corruption across the countries participating in the European Social Survey 2010. The major implication of the findings is that the data from some countries cannot be used fruitfully for cross-national comparative research.