Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers.
Ephesians 4:29, NKJV
Some people think they can eliminate foul language from their life just by resisting the urge to cuss or tell dirty jokes. While such steps can certainly be a good place to start, the heart of the issue is to speak constructively.
The word for edification in this verse, sometimes translated building up, is the term for construction. Now this does not mean we affirm every suggestion or compliment every action. We can still think critically and exercise discernment in our views.
The key is to use words that make matters better and show grace. I have not always done this. Our speech is as dangerous as a construction zone. We must exercise caution and use it only to build up and never to tear down.