While I have seen cases in which patients fake dangerousness in order to intimidate and/or to inflate the value of their claim, many of these individuals truly represent a danger. This is especially true if they are drug seeking, have a past history of domestic (or other assault) violence, a police record, and/or have been consistently labile and verbally abusive.
Do not assume the position that _this is merely a manipulation._ Often, but not always, there are warning signs of impending dangerousness. For example, the patient has made demands while being examined, been verbally insulting/demanding at the front desk, crude/rude on the telephone and/or announces that they _will not tolerate_ reasonable limitations on their behavior in the office.
Another warning sign can be the way in which they handle frustration in person or on the telephone (such as delays in scheduling an appointment, delays in being seen, or delays in prescriptions being filled.
This is another reason why medicating some patients with narcotics, especially those with past drug/alcohol histories, is very much a problem. Substance abuse *disinhibits* an individual: removes their ordinary restraint against being physically aggressive. Additionally, if they have become dependent upon prescribed narcotics, they are will to use threat and coercion to secure refill or to use violence in the prescription is not refilled.
There is a recent article regarding violence toward doctors in Great Britain, indicating that 95% report verbal abuse from patients in the past year. Just as in spousal abuse, physical violence is often (but not always) preceded by unregulated verbal attacks.