At the time I used to be part of a workshopping group, and one of the writers was working on a detective story where the main character was just perfect. Her clothes never creased, her hair was just so, she always knew the answer when everyone else was floundering. I hated that character; I couldn't stand her smug perfection and know-it-allness.
What I couldn't see was that my characters were just as flawed as her character. Her character was nothing other than perfect; mine were nothing other than nasty. Pure nastiness is just as dull as pure perfection. It's the contrast that is needed, the good and the bad. My nasty characters needed to have some nice aspects, her perfect character needed some flaws. None of us are perfect, and it's the imperfections that make us ourselves - and make us lovable.