What Makes a Character Bad

They make decisions that don’t really make sense. 
They’re bad to be bad.
They have no history.
They don’t want anything. There’s nothing driving them forwards except you, the writer. 
They’re a meh character. Nothing about them is interesting. No one cares about them.
They aren’t realistic. Maybe they’re perfect or never make mistakes or burp or have sexv because why’re an angel…all that is unrealistic, and people hate that. 
They take lives or do horrid things that any normal person would think twice about.
There’s no consequences for their actions.
They speak like no normal person would. Yes, dialogue should be spicy and fabricated but completely from the norm is unbelievable. 
They never eat or sleep so they’re not human. 
Their friendships or relationships or interactions are dry and dull. 
They have no substance – likes, dislikes, aspirations, quirks, humour, friends…
They’re a fool.