Thank you for your question! I think Caesar is fascinating to all of us. Ethical questions, however, are very hard to answer. I'll do my best, but I can't give you an answer that is 100% certain.

First, I have to establish what the "standards and morals of the time," were, which is hard. I'm going to have to make some generalizations and arbitrary decisions, so please forgive me in advance. Very generally, the traditional ethical model for Late Republican Rome was the humble, self-controlled farmer. Cincinnatus (~520-420 BC) was the traditional example: he was content working on his small family farm well into old age, he was made dictator twice in times of desperate need, and both times he happily gave up power after he had successfully defended the Republic. There are other exempla that I think are relevant here. Manlius Torquatus (~400-300 BC) was a revered general who had his own beloved son executed when the young man unwittingly violated a direct order from his commander. Fabius Maximus (280-203 BC) was a general during the 2nd Punic War who realized he couldn't defeat Hannibal in a battle, so he tried to exhaust Hannibal's army with successive retreats. While the other Romans eventually realized that this was the only possible strategy for success, Fabius Maximus was cruelly mocked and insulted by his fellow Romans in the mean time. I think all these figures together help you get an idea of what was traditionally considered to be the "ideal" Roman leader: a humble, intelligent man of simple tastes who would sacrifice anything, including his reputation and his family, for the well fair of the people. This is the ideal which Caesar's contemporaries and frenemies, like Cato the Younger or Cicero, subscribed to. This was also fundamentally an aristocratic and elitist ideal.

Of course, this doesn't sound like Caesar. But Caesar was living in a very complicated political time. In the mid-2nd c. BC the Gracchi brothers had managed to push legislation through the tribes as a tribune of the plebs without approval from the Senate, which so horrified and threatened the Patrician political establishment that they were both murdered about a decade apart. As the legislation they had forced through the tribes was intended to benefit the people from lower social classes, the Gracchi brothers became an alternative, populist ideal. This created a unique and volatile situation in the Republic. Two groups emerged with radically different ideas of how the Republic should operate and consequently, different ethical ideals. The Optimates preferred legislation with senatorial approval and associated this system with the traditional exempla. The Populares accepted the methods of the Gracchi, and were slightly iconoclastic in that they didn't appeal to these traditional exempla as frequently. It is important to note that both of these groups would probably have agreed that sexual promiscuity, over indulgence, and hunger for personal power were big no-no's.

Caesar was with the populares, which meant not only that he favored by passing the Senate, but also that he tried to project an image of mercy, competence, and generosity which was meant to endear him to the average Roman. Compare his speech in the BC to Cato's. Then read 54. While you can obviously see who Sallust preferred, I think the comparison is a helpful summary.

Sallust's shade at Caesar also provides a nice segue: Caesar was frequently the subject of some pretty crazy gossip. His sexual promiscuity was a constant concern. Catullus jokes about Caesar being penetrated by another man (a BIG no-no to almost every Roman). There were many other rumors (50-52) of his improper relationships with Patrician women. On the other hand, his long relationship with Servilia was apparently affectionate and he was a devoted father who was crushed when his daughter, Julia, died young.

So, was he a bad person? Even at the time, that would have been a hard question to answer. He certainly did not live up to the traditional ideal and many Romans (especially the Optimates) would have seen his lack of humility and aggressive pursuit of self-interest as dangerous traits. At the same time, his clementia was legendary. He was generous to the people and he avoided executing his political rivals. While his sexual preferences may perhaps have been unusual, he clearly had the ability to be a good partner and father. On top of all of that, our sources are all biased in one direction or the other, so we can't really trust much of the information we have to be 100% objective or accurate.

In the end, I'll say "no." But that might just be me.

Edited to add: One of the reasons I have a soft spot for Caesar is his apparent affection for Brutus, even as he was dying. Brutus was Servilia's son, and there were some scattered rumors that Caesar was his true father. Yet Brutus, as a Junii, was with the Optimates, and he fought against Caesar in the civil war. Later, he married Cato's daughter and even eulogized Cato. Caesar, however, always acted in his favor. During the civil war Plutarch says he gave specific instructions to his troops that Brutus should be captured alive and that even if he refused to surrender they should not harm him. Even for Caesar, that's a lot of clementia. After the war had ended, he actively promoted Brutus for prestigious positions. Even at the very end, when he knew Brutus had betrayed him, all he said was (in Latin letters) "kai su, teknon?" ("and you, my son?"). Some Classicists have interpreted this as a threat. But in my opinion if he really wanted to threaten Brutus he would have said something less ambiguous. To me, this is something a man would say when he really can't comprehend how someone he loved so much would hurt him like this.