We had a need to see whether a password was set on hosts. What I did was create a new ACI that allows search on krbPrincpalKey and userPassword. This means you can search for attribute existence and gives us a better picture of what entries have.
This adds a new fake attribute, has_password. I've added has_password and has_keytab to user objects as well so you can see whether a password is set on a user (and may be useful during migration).