A reference given by a former employer can be a deciding factor in hiring decisions. Job applicants who are concerned that their former bosses are giving out bad references can use services like References-etc.com. which pretend to be employers and report back what is being said about applicants. Although it is a helpful tool, some critics find this practice unethical. In general, employers are often reluctant to reveal negative information about a past employee for fear of being sued.
See "What are they saying behind your back?", T. Shawn Taylor, Chicago Tribune, July 22, 2003