If this person is a friend of yours,
and you value your friendship,
it is the polite and appropriate thing to do
when something of this sorts comes up.
Friendship bonds are much greater and more important
than any friends ex would ever be to you.
ALSO, guys talk about things just like females do,
so if lets say the friend and the ex lived together when they were dating
and the friend realized the ex was a slob and didnt take care of herself,
he could fore warn his friend.
understand?