I have relatives (we're all Muslims) who have mercilessly beaten the poor and vulnerable, mocked and treated the poor like they're sub-human, and just overall have vile character. As a result, I have no respect for them. I can't help but be filled with a degree of bitterness and scorn towards them. Is that considered a flaw in my character? Islamically, how are we expected to navigate such sentiments towards people like that? How far are Muslims obligated to take their compassion and humility?
When dealing with a complex issue like that, your best guide is the Quran. The Quran does not ask you to see such situations in black-and-white terms, forcing yourself to behave a certain way even if it goes against your nature. It tells you try to follow its moral philosophy in your life while continuing to use your intellect and conscience.
Therefore if you find their behavior repulsive, the Quran does not ask to continue treating them like they are close and beloved friends. It asks you to continue being nice and just toward everyone, even those who are mean and unjust toward you. But that is the limit of it. The Quran does not invalidate your thoughts and feelings, so you are free to think of them the way you described.
Umar ibn al-Khattab may God be pleased with him gave the job of governor to someone, and this person came to visit Umar the night before his departure to the area he was supposed to govern. He saw that Umar was playing with his children, who were riding him like a horse. He expressed wonder at how the ruler of the Islamic world allowed his children to do that to him. Umar asked him how he treated his own children, and the man said that when he goes home, his children all retreat to distant corners out of fear for him. Umar immediately sacks him, saying that a man who is not merciful toward his children cannot be merciful toward the people he governs.
So you see, Umar felt free to judge that man for his treatment of his children. His thinking wasn’t that he should love his fellow Muslim brother no matter what. If he sees someone being unkind, he feels free to criticize them and even takes action against them (by firing them from their job).
Life is complicated, so it is difficult to navigate certain situations. The best thing to do is to read the Quran constantly until its moral philosophy becomes second nature to you. In this way you will be able to use its teachings and your own intellect and conscience to come up with sophisticated solutions for each problem without oversimplifying things and without ignoring your own humanity and the humanity of those around you.