If a writer gives you a story and asks for your honest opinion, he doesn’t really want your honest opinion. Actually, he does want your honest opinion, but only if it begins with the words, “This is the best story I’ve read in my life . . .” Or, slightly more risky, the opinion could be modified with “one of the best stories,” which while not preferred is at least acceptable. Otherwise, no, he doesn’t want your honest opinion. If you have to lie, that’s all right. We lie to children about Santa Claus. Telling writers what you think of their work is sort of in the same category. You should be spreading hope and good cheer. You don’t want to take Santa Claus away from a writer, do you? That’s a very crummy thing to do.