Good guys and bad guys?

A coup d'etat today in Guinea-Bissau, an impoverished former Portuguese colony in West Africa, replaced the autocratic President with the Army Chief of Staff. The BBC reports that former President Kumba Yalla dissolved the government a year ago, and promised to hold elections to replace it, but delayed those elections four times, including once very recently. In reaction to the fourth delay, General Verissimo Correia used the army to arrest and depose the president. Now Correia is settling in at the presidential mansion and promising to hold elections soon.

This brings up a difficult question in Third World politics, namely, Is it alright to stage a coup against a leader in order to make the country more democratic? Does a desirable end justify an otherwise unacceptable means? What if the coup is against a democratically elected but no longer popular leader? We can't just overthrow governments to appease the public whenever they change their minds - patience is part of the democratic process. However, if coups were never staged in many countries, there's no telling how long the dictator du jour would stay in power. Of course, if their replacements are no better, why is the coup acceptable? It simply allows the country to degenerate into the stage for a power struggle between elites, a power struggle that tends to hurt many bystanders. But is it fair to say that a coup is acceptable if and only if it results in democracy? That's a flagrant case of the ends justifying the means, which is precisely the type of national leadership that democracy at its best seeks to subvert.