The workplace provides many situations in which a worker would feel pressure to talk critically about a colleague, employer or subordinate.
Employers often request that an employee evaluate the performance of a fellow employee.
Additionally, sometimes people talk about colleagues in situations when not expressly required to do so by the employer. Even these discussions are sometimes beneficial in that they enable the coworkers to express their frustration and blow off steam. This release of tension can help avoid subsequent arguments, facilitate development of strategies to deal with the colleague, or provide emotional or moral support. The issues you mentioned, evaluating co-workers and employees and blowing off steam come up constantly in the workplace and bring into focus a number of the laws of loshon hara. Saying negative things about others is, in general, prohibited by the laws of loshon hara, and is treated consistently by Jewish sources with an extremely high level of stringency.