Negative link is created by a person on review sites using his/her name and password. It is intended to harm the reputation of a reputed person or a well-established person. Though it is almost impossible to remove, some damage-control exercise can be done by pushing it in underneath pages.
If you are successful or your company has become very famous, the chances are that it will make some people envious. They may start taking a potshot on you by creating negative link on the review site. As Google gives high preference to any negative posting, it gets prominently surfaced just after being posted. Thus, even a slightly negative content can sink a company or soil the image of a person irretrievably.
"The greater the difficulty the more glory in surmounting it. Skillful pilots gain their reputation from storms and tempests."- Epictetus