The effectiveness results from the impression that the irrational negotiator is willing to take great risks and to hurt both sides if he doesn’t get what he wants. This carefully planned impression is used to persuade the counterpart to meet all demands. Irrational negotiators use distribute tactics very efficient, because they are able to express strong negative emotions in a very credible, convincing way, in a situation where there is a lot at stake. If you are negotiating with such people, you start believing that your counterpart would rather walk away from the table, then settling for less than his optimum.
Some negotiators are able to play this behavior. Many people try it, few succeed. Most fail, because you have to know exactly when to act angry, with which person, to what extent and at which specific time. Negotiators who are able to play negative emotions, are using them usually in a rational, manipulative way.
Maybe the most common action of an irrational negotiator is to make an outrageous first demand, in order to increase the possibility that the second (smaller) request will be accepted by the counterpart. Psychologically it is understandable. The second request might seem much more reasonable with compared with the first (extreme) one, rather than standing alone.
One other reason why irrational negotiators might be successful, is because of the escape behavior of the other party. Most people don’t feel comfortable in a hostile, aggressive and negative environment. Some times it might happen, that the counterpart accepts the offer only to have the irrational negotiator be quiet. By doing this, one party rewards the hostile behavior of the irrational negotiator, who will learn that his strategy was successful. The likelihood him using the same approach in future has increased. The inferior party will feel offended by the provocative behavior, and he will become angry too, will express the desire to hurt you, rather than to satisfy his own interests.
As you can see, playing negative emotions to manipulate the counterpart will most likely backfire in future interactions and the negotiation is very likely to break down.