Don't be fooled when people say they want their problems solved for what they really want is to be told is that someone else is responsible for the problems they, themselves, created. What they really want is confirmation their incorrect opinions are correct.
If you advise them their opinions are correct when in-fact they are wrong, they will come to see you as a bad advisor. When things finally fall apart they won't come back to you and will tell others it was your fault. If you honestly inform them their opinions are wrong they will go away angry, still commit the same mistakes, then come back again only to get angry with you again because you again refuse to confirm their opinions.
So after many years of being asked to confirm incorrect opinions I've come to the conclusion it is best to simply tell them I don't know the answer even if I do know the answer.
No, they're not happy with that either but it forces them to find someone else to blame for their mistakes rather than blaming you.