When legalese gets down to defining professional ethics, you come up
with some strange conclusions.

I don't think physicians run around town telling every overweight smoker
that they are probably suffering from circulatory and lung disease.

You could argue this either way.  Unethical to stick your nose into
someones business when they haven't asked you for professional help
or it could also be construed as unethical for you to see a problem
and not inform the individual of that problem.

For me, I try and use common sense.  I don't tell everyone I see of
dental maladies that they exhibit.  However, I will certainly try to
find ways to enlighten them if the setting allows this to be done in
a friendly, tasteful manner.

JMO,
D