Daf Yomi recently has provided more instances of dubious ethical behavior (see my previous post Were the Amoraim really paragons of virtue?).
1. The Gemara (Bava Basra 8a) relates the following story. There was a famine and Rebbe (who was rich) opened his storehouses to feed people. However, he refused to provide food to עמי הארץ. R' Yonasan ben Amram came to Rebbe and pretended to be an עם הארץ. Rebbe refused to provide him food. R' Yonasan ben Amram said to Rebbe feed me just like you would feed a dog and Rebbe gave him food. After he left Rebbe was upset with himself that he gave food to an עם הארץ. Rebbe's son told him that maybe the person wasn't really an עם הארץ but rather was a talmid who didn't want to benefit from his Torah. After that Rebbe provided food to all. The question is obvious. How could Rebbe be so cruel and not provide food to an עם הארץ? The Kovetz Shiurim is bothered by this question and doesn't have a good answer.
2. רב אחדוי asked רב ששת a question and laughed at his answer. רב ששת got upset and because of that רב אחדוי became mute and forgot his learning. Someones mother (either רב אחדוי or רב ששת) begged him to pray for רב אחדוי and when he refused she bared her breasts and said see these breasts that you nursed from and have mercy on Rav Achdevoy and pray for him and he did and רב אחדוי recovered. Again, we see an Amora get insulted and lash out at the insulter causing him great harm.