Don Vincente is the man that Gould and his friends help to put in power as President-Dictator. Don José describes him as the "hope of honest men" (I.8.46). Supposedly he was a fairly solid dude, a "man of culture and of unblemished character, invested with a mandate of reform by the best elements of the State" (II.8.45) who had to be convinced to take on the five-year term of presidency. So, he was basically the one guy in Costaguana who wasn't power hungry, it seems? Hey, maybe he could have been good.
Of course, his reign lasted a only hot second; basically, right after coming to power, Montero (his minister of war) led a revolt, and he had to flee from the country