Law enforcement have been charged with disrupting growing amounts of online criminal trade, using methods such as taking down criminal marketplace infrastructure and arresting cybercriminals involved in these networks. However, decreases in trading volumes following these operations have only been temporary. Slander and Sybil operations have also been used more recently in order to undermine these marketplaces’ verification systems and incite mistrust among their members, by respectively leaving false feedback to vendors and creating fake profiles participating in fictitious trade together to build their reputation before defaulting on sales made with non-fictitious buyers. How do cybercriminals respond to slander and Sybil operations conducted on their marketplaces? This article discusses the findings of a social laboratory experiment which replicated online marketplace conditions in order to ascertain whether slander and Sybil operations have an impact on the price and/or quality of products sold on the marketplace and their effectiveness at disrupting trust between traders in a controlled environment.