There is always one in every office.

Trust is a key component of any successful company or team, and it only takes one problem employee to kill the atmosphere.

This will naturally lead to decreased productivity over time. Snitching is also bad for employee morale and camaraderie; who wants to be friendly with people that might stab you in the back?

Besides creating an overall dysfunctional workplace, tattletales can also lead to increased employee turnover, costing a business the time and money it takes to recruit new hires.

Below is a good resource on how to both identify those individuals as well as how to deal with them in the workforce.  I learned a couple things after reading the article, and definitely need to think twice next time I'm tempted to fight "fire with fire" or loose my temper from their actions.

Source.