In an article titled “Learning Unethical Practices from a Co-worker: The Peer Effect of Jose Canseco,” published in Labour Economics in 2011, Eric Gould and Todd Kaplan use baseball player Jose Canseco to study peer effects among co-workers. Their analysis focuses on Canseco spreading knowledge of performance-enhancing drugs to teammates. The authors claim to find evidence of Canseco’s influence through the improved performance of his former teammates. This paper reexamines the performance of Canseco’s teammates and finds no empirical evidence of a performance improvement among Canseco’s teammates. In addition, I contend that Gould and Kaplan’s own empirical findings do not support some of the claims they make.