The Tongue II

The second situation is the case of a person who did not initiate the shidduch but has been asked for advice on whether the shidduch should be looked into.
This person has a greater responsibility than the first who suggested the shidduch because the first was only giving a possible suggestion but the second person is called on specifically for a definitive opinion which may make or break the shidduch.
The person called for advice must be careful not to encourage or discourage a match with someone he has no real knowledge of.
If all this person knows is hearsay, they should not express an opinion because what they heard may be totally false. If they do not know the person this should be stated.

An adviser may be sought by a family that has had a shidduch suggested by someone they do not know well. They are unsure whether they should follow up with this suggestion, or maybe it has no merit and may be ignored. The adviser should deal only in facts. Feelings are not what is required at this point. The adviser should look at the shidduch suggestion and express an opinion only based on facts. If the adviser thinks personally that they would never have suggested such a shidduch, that has no bearing on the situation. Their advice has to be based on concrete reasons, on real concerns based on personally known facts and not on second or third hand information. Although the adviser's first loyalty goes to the person asking their advice, they are certainly forbidden to discourage a shidduch unless they have firsthand knowledge of the matter that could cause problems, and it is proven that this matter should be of concern and is not just a mistaken impression.
If one is not sure of the answer to give, it is certainly proper to tell the person calling that it is not a convenient time and ask to be called back later. In the meantime call a Rov and ask his advice on how to approach this situation.