Chapter 2, Stereotyped Knowledge, examines irregular practitioners’ global trade in cheap manuals on venereal disease, sexual debility, and fertility problems. While previous scholarship has largely focused on these manuals’ lurid depictions of weakened male bodies, this chapter emphasizes their origins in respected publications: often calling themselves “consulting surgeons,” a term from hospital practice, irregular practitioners combined verbatim sections from textbooks and treatises aimed at medics with snippets from works in other genres to construct their own “popular treatises.” Some of these productions were issued in several different languages and circulated around the globe. At home and abroad, they offered readers an affordable means of acquiring modern information about sex reproduction, derived from the science of anatomy, and their authors a means of cultivating trust in their expertise and advertising more expensive products and services. Examining other medical practitioners’ responses, this chapter argues that these manuals and their makers were seen as both an economic and existential threat to regular medicine.