An early 19th century book on deception describes the following case: a soldier reported sharp pain and reported having a "rupture" (or possibly a hernia, the details weren't precise). When the army surgeon examined him, he found that the "rupture" had been self-inflicted. On further investigation, he was also found to have a complete set of written instructions titled (what else?) How to make a rupture. Apparently previous soldiers who had succeeded in fooling their doctors had passed on directions for other soldiers who wanted to do the same. The soldier in this case was discharged by his commanding officer but without a note from the army surgeon, he didn't get the pension that could have gone with it. The commanding officer checked on the soldier after some time and found him "perfectly well, following the laborious occupation of a porter".
For as long as there have been medical doctors and an incentive for faking, there have been fakers. The patron saint (as it were) of fakers was certainly Odysseus (a.k.a., Ulysses). According to Greek mythology, Odysseus tried to avoid taking part in the Trojan war by pretending to be mad. He even hitched up a donkey to a plow and began sowing his fields with salt. His recruiter, Palamedes (probably the patron saint of medical examiners) put him to the test by dropping Odysseus' infant son in front of the plow. Odysseus was forced to drop the insanity act and never forgave Palamedes for the trick (thus beginning the long war between fakers and examiners).
Examples of medical fakery have been recorded as far back as Roman times, only the reasons for faking have changed. The same text on deception describes a number of other examples of faking by soldiers in the British army to secure a pension or otherwise escape being called into combat (PTSD was unknown in those days, only physical injuries were considered grounds for military discharge). Soldiers tried different ways to fool the army surgeons (often with helpful advice from family or friends). Substances used to fake symptoms included silver nitrate, large doses of tobacco, Spanish fly (which had more than one use), belladonna (for faking blindness), and assorted other herbal compounds.
Sometimes the trick worked too well. In 1804, a military surgeon became suspicious about the sharp rise in opthalmia (pink eye) cases. He investigated further and found that the soldiers in the military hospital had arranged for friends on the outside to send them quicklime and copper hydrate to put in their eyes to simulate the opthalmia. When questioned, the soldiers provided the names of other soldiers who had managed to get medical discharges using the same trick (so much for solidarity). All of the soldiers involved were convicted.
There seemed to be no limit to the ingenuity involved in faking different diseases. Tuberculosis (a.k.a., consumption), paralysis, loss of sight or hearing, or "accidental" injuries were all simulated at one time or other. During the 18th century, army surgeons learned to keep a constant watch on soldiers with suspicious injuries to see if the symptoms persisted when the soldiers weren't aware they were being watched. Doctors often resorted to trickery including firing off a gun behind the back of "deaf" soldiers to see how they reacted or observing "paralyzed" soldiers who were recovering from anesthesia to see if the paralysis was present before they were full awake.
While avoiding military duty tended to be the most commonly reported reason for faking medical illnesses in the early literature, new motivations for faking diseases arose with the introduction of social legislation in the early 20th century. Faking became potentially profitable due to compensation for injuries resulting from industrial and automobile accidents as well as the growing attraction of litigation settlements. Medical professional gradually learned to be more aware of potential faking when dealing with unusual or obscure symptoms. As medical testing became more sophisticated, cases of symptom faking shifted towards more obscure diagnoses that were harder to put to the test.
The latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) formally identifies several diagnoses associated with faking. The most commonly known diagnosis, malingering, is used in suspected cases of faking that involve an external reward (i.e., is there a payoff for the faking?). Other diagnoses where faking can occur include factitious disorder (faking to gain attention or nurturing) and Munchausen syndrome which is a specific type of factitious disorder motivated by a desire for attention from health professionals. Cases of Munchausen syndrome by proxy with caregivers (often mothers) deliberately causing health problems in children has received considerable media attention but the true incidence is unknown (and the diagnosis has been successfully challenged in court). Other terms such as compensation neurosis and pseudologia fantastica are still used at times in faking cases. I won't even try to explain these different diagnoses in detail, so I'll just be focusing on malingering.
Problem diagnoses including conversion disorders, postconcussional syndrome, mild head injury, environmental exposure, chronic pain, and fibromyalgia/Chronic Fatigue Syndrome continue to be controversial and accusations of malingering are common. Physicians are often bombarded with requests for potentially addictive pain medication that must be carefully weighed to separate legitimate cases from drug-seekers. Clients presenting with mystery symptoms that have no apparent physical basis need to be screened by mental health professionals to test for potential malingering. Cases involving deliberate self-exposure to toxic substances are still being observed although not as frequently as in the past.
Different diagnoses and presenting symptoms have led to the development of multiple criteria for diagnosing potential faking which have been shown to be reasonably effective although problem cases still occur. Clinicians have learned to watch for any discrepancies between what the patient is presenting during the actual interview and how they behave when they think they aren't being observed. Insurance companies routinely engage in covert surveillance of patients engaged in litigation and often provide the surveillance tapes to clinicians to include in the assessment.