Have read tons on big pharma and their illicit practices. The detailers (or drug reps) are chosen for their looks first - college cheerleaders are often approached. Their job is to document what types of inducements influence doctors. They already know their prescribing habits because chain pharmacies supply the reports, and the numbers used to theoretically protect doctors' anonymity are undone by the report pharma buys from the American Medical Association.
Medical journals are largely controlled by big pharma - their so-called peer reviews are often far from objective. One editor, of The New England Journal of Medicine
no less, quit in disgust.