The most rigorous examinations of a trained person's qualifications and competence occur at the beginning of their careers and rarely, if ever, again. Maintenance and upgrading of skills may be encouraged, but is largely optional. Professional associations which have the responsibility for overseeing standards, and dealing with complaints about individual practitioners, rarely take action to prevent that peron from practising. Professional success or reputation may be won more by personal charm, or by the simple market mechanism of supply and demand, or the inbuilt prejudices of the system, than by ability or character.
Professional self-regulation is ineffective. It is usually the case that unfit practitioners first come to their attention of professional monitoring bodies when they are convicted by the courts or the subject of formal public complaint. Since only cases which suggest seriously poor performance attract the procedures of professional investigative bodies, the less serious, but nevertheless potentially disastrous cases remain.