You've been psychologically tortured and abused by a narcissist/sociopath/psychopath family member. You finally tell another family member what you've experienced. What you get back from this person is a "sermon" on how there is good in everyone. You haven't looked hard enough for it. Everyone has redeeming features; if you haven't found them then you are just not looking.
Implied in this sermon is that the deficiency is in you. Also inherent in these comments is the belief, perpetuated by humanistic psychology, that everyone is basically "good". There is no room in this anthropological theory for the concept of evil. Bad people don't exist. Malevolence is a figment of your imagination.
The person who says things like this to you has something to gain. Perhaps they are trying to keep you from "rocking the boat". Maybe this land of denial they live in is how they keep from having to deal with anything difficult. Fear of confrontation. Fear of standing on principle. Lots of people are afraid of principle if by having one it'll cause them some discomfort. So they become unprincipled which allows the evil people to flourish.
So, let's get back to the idea that you just need to look harder and find the "good" in the person who makes a living by sucking your life from you. First of all, if you have to hunt that hard to find some good in someone it simply isn't there. Another thing is this: there are many deeds a person can do that can appear to be "good" but are not. Look closely and you'll see the "good" done by a consistently evil person is self-serving. They try to appear good in certain situations (i.e. when others are looking) so as to get away with being evil! It is a ruse. A guise. An occasional "good" deed does not weigh the balances against a consistent life of bad deeds.
Let's look at a historical figure. I think most reasonable people can agree that Hitler was an evil man. His complete obsession with wiping the Jews, gypsies, people of Slavic origin, mental deficients and the physically impaired off the face of the planet seems to be sufficient evidence to decent people that this man was an evil psychopath. What good deed could he do that would be adequate to the task of mitigating his evil? Again, reasonable minds could probably agree that nothing he could do would be good enough to outweigh the vast evil of his homocidal hatred of certain classes of people. Some people have actually tried to find the "human side" of Hitler. He loved animals. He was vegetarian. He was able to unite Germany. These are some of the things brought up by apologists for Hitler who try to minimize his evil. He wasn't evil, he was misunderstood. He was a little misguided in some respects, but he was a great leader. Okay, if that works for you then you can go surf off somewhere else because I can't say anything that you will agree with. The truth is that there was no "good" in Hitler that could outweigh his evil deeds. It is rare for a malevolent, evil person to have no qualities that can be construed to be "good". For the naive, the ridiculously stupid, or other evil people, those "good" qualities can outweigh a life of consistent evil. For the sane and principled those "good" qualities are seen for what they are...a mask. An aberration. Yes, for the evil person a "good" deed is an aberration!
So what if you can find some "good" in an abusive person. If you have to hunt around, stretch your imagination or wrack your brain to find the "good", then, honey, it just tain't there. Face facts. Don't let yourself be confused by the silly idea out there that if you can find ONE good thing in someone then you have proof positive that person is not evil after all. It is that kind of thinking that will keep you enslaved. You are allowed to call evil by its right name. You are allowed to distance yourself from it. It is called self-preservation. Self-defense is a fundamental right of all living creatures. Exert your right to live. Shrug off the small-minded thinking out there that puts on such a pretense of bigness and righteousness by pretending that evil people aren't evil. In my mind, these mental midgets are just as dangerous because they do nothing to stop evil. Their stupid philosophy perpetuates evil. Distance yourself from the evil people in your life...and that includes the idiot who tells you to hunt for the good in an abuser.