Okay, let me expand.
So, first of all, what do I mean by "bad parents"? Obviously, as Martinius' post showed me, we have Very different interpretations of the idea of bad parenting. Let me give an example of what I'm talking about.
Suppose there was a couple. A Christian father and a mother who professed Christ, but who had actually been lost the whole time. Now suppose this couple had children. The father raised his kids to believe that there is a God, to understand some of the Christian faith, but these kids hadn't become Christians themselves. The mother, in the meantime, gradually loses herself in her sinfulness and perversion until one day she reveals to the family that she has been an unfaithful wife and that she is leaving them for another man. One of many men she has been unfaithful with.
She still wants to be involved in the kids' lives, but now they don't know how to treat her because, despite the commandment that she is their mother, they cannot accept what she has done to them and their father. The commandment, "honor thy father and mother" becomes a huge problem in this scenario because what does it mean to honor a mother who has so blatantly rejected not only Christ but the sacred covenant that is marriage. She has renounced her family.
This is a common story. Not just for mothers, but for fathers as well. Parents of both genders abandon their families and their commitments to serve a desire they clearly love more than they claimed to love those around them. Bad parenting, in my book, means neglecting your children. Not merely in the extreme situation of not feeding them or beating them or even forgetting they exist. Rather in the more common way of putting certain agendas and desires above the needs of your family.
It is a tricky question, and I wish someone would take it more seriously than you guys have been taking it so far. But maybe that's my fault. Maybe I should have been clearer. So here's more of what I was talking about. Does that help?