Let's say the guy is an incredible psychopath. This means most people won't connect with him. But the way he acts may fascinate them and that makes him a good character. Throw a few likable things like he has a moral rule of not harming children and boom, you have a good, likable character.
May I introduce you to Khada Jhin, The Virtuoso from League of Legends? He's one of the most deranged psychopaths in fiction and people absolutely love him. Outside of his kit as a playable character, his written persona is amazing, consistent, and one of the best Riot has ever produced. He works really good in the plot and as a standalone as well. There is literally no redeeming qualities to him, none. He's a madman that kills his victims through the lens of theatrics and his approach to insanity if you will is what draws people in. You won't find any gram of simpathy in him, and that doesn't make him a villain either because he's not evil for the sole purpose of being evil.
Characters should never be one dimensional in good and evil. A fluffy rabbit that harms nobody and accepts everybody can be a predatory capitalist despot and still be lovable. A serial killer that includes children as victims may do so for social justice and the safety of the downtrodden and still be lovable. It's a mix of motivations/goals/actions/desires/needs/wants that make a good character. Not the avoidance of a particular evil but the justified approach to said evils. The line should be so blurry it makes you feel complicated. You know... like real people?
A character that never does 'bad things' is plain at best and a mary sue at worst. A floor mat if you will. Harmless instead of peaceful. They will act only as a reaction to events rather than being proactive in the plot.
And we arrive to that annoying question: Who are you writing for? Do you want to make plausible characters within a narrative or do you seek the projection and acceptance of readers? Some may love the rabbit, others will stan the serial killer. But every reader will await the day the two meet and shit goes down.