You are right that people are not able to exercise discernment. In my former church the pastor had one young lady ask him for a "list of what she could and could not do" before going off to college. He called her mom and dad in for a family sit down because if, at this point in her life, she was having to ask there was something seriously wrong.
The biggest problem is that they may hear one thing from the pulpit and hear something else at home.
I agree completely.
When my kids were growing up, we lived in a welfare town and saw more stuff than I'd have liked, but it did give us the opportunity to discuss bad life choices and reinforce right and wrong.
When they went off to college, they never asked me or anyone for a *list*.
All three of them are now pursuing grad degrees, and nobody ended up on drugs, in jail, pregnant, or whatever.
They knew what they believed and why they believed it.