We have seen that a derogatory statement about someone is not to be believed as fact even for a constructive purpose. One is to take the necessary precautions without changing his attitude towards the subject.
We have also learned that to cause another Jew to transgress is to violate the prohibition, “Before a blind person do not place a stumbling block.”
Consequently, when one relates negative information for a constructive purpose, he must be careful not to cause the listener to sin by believing the information as fact.
The proper way to convey negative information for a constructive purpose is to preface it with a statement such as, “Don’t take my word for it – I may be mistaken – but do take the matter under serious consideration”.