To begin with Tuco, "the Ugly", we see a human being at his basest level. He acts on instinct and appetite, with little consideration for others, and with little dignity. He is clever, but not intelligent. He can act kindly, but he is not kind. In one scene, as he is facing the hangman's noose, Blondie is waiting to shoot the rope to free him and listens to a recitation of Tuco's given name and calls him "The Rat", pointing out that animalistic character.
According St. Thomas Aquinas, when a man behaves as an animal, he is worse than an animal. By surrendering our dignity and reason, and instead living at the level of an animal, we betray those qualities that make us most human. When we look around these days, it is relatively easy to see those of us who have sunk to the level of "the ugly" (an occurance made easier through reality TV).
Our final type is "the good", Blondie. He is never cruel for its own sake, rather he makes an attempt to act in as kind a manner as a situation warrants. Yes, he does take part in a confidence game with Tuco, bringing Tuco in for a reward, then shooting the hangman's noose before Tuco is strangled to death, then "capturing" him again and bringing him in for the now slightly higher reward. But this form of employment for Tuco is different, as no one comes to harm. Even Tuco comes out ahead.
In a later scene, when Tuco has taken Blondie to a monastery for treatment for exposure and heat stroke, Tuco meets his brother, and, far from a touching reunion, the elder brother fights with Tuco and casts him out. On the road out, Tuco attempts to cover his shame and loss by making up a story about how his brother begged him to stay, and offered his welcome whenever he would come, all of it obvious lies. Blondie knows all this is a lie, but lets it be, even offering a cigar to Tuco, as a perfect ending to a meal.
Another scene which shows this quality is when Blondie meets a dying confederate soldier, and offers the dying young man a smoke. There is nothing to be done, he can't save him, but he does offer some comfort to someone in need. And this seems to be the point of a good man. He acts with compassion for those around him, taking pity on suffering, and never seeking to capitalize on those in need.
So which one are you?