This study examines two dark-pattern cues in online travel agencies (OTAs)—social proof and time-scarcity messages—and how they relate to impulse buying intention via the urge to buy. It distinguishes a direct pathway from an indirect pathway through anticipated joy and regret, and tests whether these pathways vary by need for cognitive closure (NFCC). Scenario-based survey data from 509 U.S. OTA users were analyzed using covariance-based structural equation modeling and multi-group analysis. Social proof was positively related to the urge to buy, directly and through anticipated joy and regret. Time scarcity was positively related to both anticipated emotions but had a negative direct relationship with the urge to buy. NFCC did not simply amplify these relationships: social proof was more strongly tied to anticipated emotions among low-NFCC consumers, whereas the contrasting time-scarcity pattern appeared only among high-NFCC consumers. These findings highlight heterogeneity in responses to dark-pattern cues across cue types, pathways, and levels of NFCC, with implications for ethical OTA interface design.