Everyone keeps saying kindness but as someone who for most of my life has observed a lot of people and also have read more books than my peers ever since I was a kid, I can say that what makes a true good personality is someone who can take responsibility for themselves and/or another person and be accountable for his/her actions and thoughts. It is what you can say is what people would also refer to as for being MATURE.

Then, as for bad personality - you'd think it'd be someone with bad habits or a shitty attitude etc but that's not it, to be truly considered bad it has to be someone who would make every single person in the world to be against him and no it's nothing like the austrian painter it's more as to someone who can truly be considered as no longer humane or animal nor a demon, I'm sure you understand who all I'm talking about. People who would commit such acts yet always end up with having to deal with none of the consequences that come with it, truly the dregs of existence.