I do not speak Italian and need your help verifying that such caption would be grammatically correct. Would that translate into "The scoundrel Vincenzo"?
Such a caption would be grammatically correct. However its meaning is different from the one you assume. A better translation would be
The cantankerous Vincenzo
To give you an idea of the connotation of the word bisbetico, the feminine form bisbetica is how the English word shrew in the title of Shakespeare famous comedy The Taming of the Shrew.