Bad Parents
Judgment about good (or bad) parenting is not static; especially if you keep cultural parenting differences in mind. One's own yardstick should not be used in appraising others' parenting style. Having said that, I still cannot help myself from reacting whenever I hear horror stories about parenting gone wrong.
Almost always, I assume that ALL parents have their kids well-being in mind. Unfortunately, that is not the case. Parents Behaving Badly has some horrifying stories to tell.