I agree with Una.Don't even mention their "care" techniques, but conversationally tell them about "this Great site with tons of cool pictures and people to chat with" and let them absorb the wisdom.
If they don't, then they are truly hopeless cases and you should just forget about them, lest it drive you mad.
It's true, you can only suggest, not tell. Keep it light and you might help them without their knowing it.![]()