Of course not. Some terrible parents are good people who make terrible mistakes while trying to be good parents (think cults) or who do things that the kids perceive as terrible.
Are parents terrible because they beat their kids when they behave badly. Or are they good parents trying to discipline their kids? It depends on whether you believe that hitting kids is wrong.
My daughter thinks I'm a terrible mother right now because of something I did on Tuesday. Parents and kids do and think things for different reasons and we don't always see it from one another's point of view.
Some parents though are both terrible people and terrible parents.