Does Online Anonymous Market Vendor Reputation Matter?

Reputation is crucial for trust in underground markets such as online anonymous marketplaces (OAMs), where there is little recourse against unscrupulous vendors. These markets rely on eBay-like feedback scores and forum reviews as reputation signals to ensure market safety, driving away dishonest vendors and flagging low-quality or dangerous products. Despite their importance, there has been scant work exploring the correlation (or lack thereof) between reputation signals and vendor success. To fill this gap, we study vendor success from two angles: (i) longevity and (ii) future financial success, by studying eight OAMs from 2011 to 2023. We complement market data with social network features extracted from a OAM forum, and by qualitatively coding reputation signals from over 15,000 posts and comments across two subreddits. Using survival analysis techniques and simple Random Forest models, we show that feedback scores (including those imported from other markets) can explain vendors' longevity, but fail to predict vendor disappearance in the short term. Further, feedback scores are not the main predictors of future financial success. Rather, vendors who quickly generate revenue when they start on a market typically end up acquiring the most wealth overall. We show that our models generalize across different markets and time periods spanning over a decade. Our findings provide empirical insights into early identification of potential high-scale vendors, effectiveness of "reputation poisoning" strategies, and how reputation systems could contribute to harm reduction in OAMs. We find in particular that, despite their coarseness, existing reputation signals are useful to identify potentially dishonest sellers, and highlight some possible improvements.