Question: I'm trying to create a character that will be disliked by some of the characters and be hopefully not so appealing to the reader. But I don't want it to seem like I'm just making him a complete piece of trash to force that impact. Is there a way to make a disliked character a "complete" person yet still get that unpleasant vibe?Answer:
In this respect, characters in a book should mirror characters in real life.
Everyone believes they are a good person and most people want to be seen as good by others. A person can be liked by friends and family, but still make plenty of enemies.
You may only need one issue, one thing about your character, that makes the reader and some of the characters dislike him. It could be a habit of acting a certain way in certain situations - an insensitivity, a disregard for others, or any of the seven deadly sins (wrath, greed, sloth, pride, lust, envy, and gluttony). Okay, maybe gluttony is politically incorrect these days, but perhaps we could stick "bragging" in its place, as that can tick some people off, or "selfishness," "unfriendliness," etc. It could be something big or something small, depending on how disliked you want the character to be.
Again, depending on your story, it could be something he did a long time ago that certain people know about. He may even have changed since then, but everyone who remembers the incident still blames him for it. In that respect, some characters can be disliked for something they didn't actually do but were blamed for nonetheless.
Even if your character is evil in a big way, softening him a little in one aspect or situation can actually make him seem nastier (like the way Ernst Blofeld in the James Bond films shows affection for his pet cat).
See, you are free, as the writer, to stack the deck against your character a little or a lot and just as much as you need.
But I do agree with you that characters who are evil through and through are rare in real life and come across as two-dimensional in stories. Even Hitler had a wife who it seems cared something for him (though she did attempt suicide twice during their relationship).