Parents who are willing to throw their own kid's parent under the bus are very selfish. They're doing it for their own gain.

For a parent who puts their child's interest above their own will keep their comments to themselves. After all, I have some negative thoughts about my son's mom, but I keep those opinions to myself as telling them to my son can only hurt him. Why would I want to hurt my son with bashing of his mom? I'll be a good parent

All these parents are doing is transferring their contempt towards a parent onto a child who doesn't want to (and shouldn't) hear bad things about their own mommy or daddy.

These parents are petty, insecure, angry, and need to grow up by keeping your child out of the divorce. If the other parent is that bad, you should be able to just sit back and let your child figure that out on his own...