One of the things that a serious engagement with Ecclesiastes does is show you how Koholeth pit one proverb against another to show how the wisdom of both proverbs was not ironclad. Even within the wisdom literature itself this is observed. A proverb employed by a fool is useless. A fool may consider himself wise for coining or using proverbs but it hardly means the fool is wise.
Some axioms in the circles I was in became popular, such as the claim that soft words produce hard people and hard words produce soft people. A variation would be the claim that the most loving thing you can do for someone is tell them a hard truth. But it takes little thought to realize that telling someone what you're sure the truth is is not exactly the same as telling them that truth because you actually care about them. One of my blogging friends has been ruminating on this lately and notes that if you share the truth without actually loving a person then it vitiates even the value of what truth you may think you're about to tell. Ephesians 4:15 may get trotted out as a pretext to tell the truth by people who want to tell it like they see it rather than do so out of love for a person. Even Judas could observe that a perfume could have been sold for a great sum of money that could then be used to help the poor. That was true but it had nothing to do with what was in his heart, did it?