Deploying robust fraud detection strategies for online marketplaces requires understanding the specific mechanics of how bad actors manipulate goods-based transactions on classifieds platforms. Fraudsters no longer rely on simple account takeovers; they now orchestrate coordinated attacks involving swapped merchandise, forged logistics documentation, and deliberately misleading courier relationships to bypass conventional fraud filters. The resource details how goods substitution occurs at pickup or delivery stages, explains the technical and behavioral signals of fake receipt generation, reveals how fraudsters abuse courier partnerships, and maps the organizational structure of triangle schemes that distribute risk across networks. Teams responsible for trust and safety, payment fraud, and seller protection will gain actionable insight into where their current detection systems have blind spots.