A growing body of literature points to the possibilities offered by postsurvey interviewer observations as a source of paradata to obtain insights into data quality. However, their utility in predicting actual behavior of respondents has attracted limited scholarly attention so far. Using data from Round 7 of the European Social Survey, we aim to clarify the relationship between interviewer observations and response styles (straightlining, item nonresponse, use of middle and extreme categories). We contribute to previous research by empirically verifying whether interviewer observations in face-to-face interviews can be effectively used as accurate predictors of data quality. Findings suggest that interviewers' assessments of response behavior to some extent reflect response styles and can potentially be a valuable tool for the evaluation and improvement of survey data quality, although this seems mainly restricted to the most overt (i.e., easily observable) response styles.