Peacekeeping has been a lot easier to get involved in since the Cold War ended in 1991. During the Cold War, the Russians (the Soviet Union) still maintained that they were the "vanguard of world revolution," and supported just about any anti-Western rebels out there. Because Russia had a veto in the UN, it was able to stop any UN peacekeeping operation it did not approve of. This murderous mischief eventually contributed to the collapse of the Soviet Union, as adventures in Afghanistan and elsewhere proved very expensive, and often embarrassing as well.
Freed from the Soviet veto, the UN got into the peacekeeping business in a big way, and failed spectacularly. You'd never know this from reading UN press releases. Even before the Cold War ended, the UN had decades of experience in issuing glowing press releases to cover up yet another boondoggle. It was never much of a secret that the UN bureaucracy was corrupt and inept, but the UN was considered such a valuable diplomatic forum that everyone pretended all the bad news didn't matter. The UN had perfected the art of waiting around for something good to happen, then taking credit for it. When bad things happened, you could always find someone else to blame.
The UN developed a pretty slick routine for peacekeeping. In most cases, their peacekeepers came in after the fighting was over and peace was breaking out anyway. This was because a major problem with the UN was that they were very reluctant to get involved in any fighting ("peacemaking"), even if such action would save many lives. There were any number of bureaucratic maneuvers the UN could employ, without even bothering the members for a vote, to avoid a possibly dangerous peacekeeping situation. There is a practical, or at least political, reason for this. Many UN members are tyrannies, who regularly kill their own people in large numbers. If the UN should suddenly get active about taking care of situations where thugs are killing innocent civilians, many UN members would be highly qualified targets. Thus the UN peacekeepers must be very peaceful, even if atrocities are committed in the vicinity of the peacekeepers.
Once the UN peacekeepers are in the field, a major concern is minimizing bad news getting out about misbehavior among the peacekeepers. The UN pays a rate that is below what professional troops from the West get, but above what professional and conscript armies in less affluent nations get. As a result, the UN takes what it can get, usually from less affluent nations. Many contributing nations are not keen to send their best troops, so the ones who show up for peacekeeping are a mixed bag. Some of them are poorly trained, led and disciplined. These guys get into trouble, with women, with looting and with stealing from the UN. Officials from the UN prefer to keep all the embezzlement to themselves, as that makes it harder for the media to get hard evidence.
The UN peacemaking programs emphasize looking good over actually accomplishing anything. Which is why most UN peacekeeping operations later turn out to be more smoke and mirrors, than anything of substance. The UN denies this in general, but gets nervous when you get down to details.
Many people working for the UN mean well, but, let's face it, an international bureaucracy only functions if the least number of member nations are offended. Emphasis on the least. Someone is always hacked off about something. For example, the United States has long been critical about the corruption and inefficiency. The UN attempts to placate the U.S. (which is, after all, the largest contributor of funds), but cannot really crack down on the corruption too hard without offending nations that hold the majority of the votes in the UN.
So the next time you see mention of "UN peacekeepers," keep in mind that there's a lot more than peacekeeping going on.