It is only possible to live a new life in Christ when the habits of the old life have been repudiated (Ephesians 4:17-32).  Lies, and anger and stealing must go.  Today, 'unwholesome talk' is in the firing line.  Although this kind of communication can sometimes be true and not sound angry; it still does no good.  Paul is including lies, gossip, flattery, spreading malicious rumours, negative, critical and hostile communications as well as the sniping and complaining that are all too prevalent in public services or large corporations.  

It is not just the words but also the tone of voice or accompanying body language.  So too is the double-entendre, the sleazy innuendo or inappropriate personal comment.  Electronic communications should also be considered, because they are less nuanced and can have an even greater potential to damage confidence, reputations, relationships and workplace performance (Ephesians 4:31).

'Unwholesome' is, by definition, harmful.  It does not build up or edify; instead it tears down trust and reputation and goodwill.  Like all Satan's plots, it appears morally neutral but is actually damaging.  It is usually destructive to good relationships, and it always harms the perpetrator's moral integrity.  The fact that we hear it all around us - to the point that it becomes 'normal' does not mean that it is ok (although that is what we are tempted to think).  No, the Christian is called to be different and, interestingly, the world expects people who follow Jesus to reject that talk-style.

New life in Christ also means a new way of speaking: not a more cultured accent, but speech that comes from a heart of love for Jesus.  He never used any unwholesome talk; instead, He spoke the truth in love, always (Ephesians 4:15).  Anything different has an evil origin (Matthew 5:37).  As Jesus was keen to communicate truth that would build up people, so should we – even if we are provoked by slander or lies (Romans 15:1-4).  In a broken world with its endless trail of destruction, there is a lot of building to do.  Feeding people's minds with truth, expressed from a loving heart will do wonders for the church and your community at work.  They may not receive the gospel immediately, but many will value a cheerful person who is wanting the best for others and only says what is true and does what is kind.  That sort of kindness is also an essential 'appetiser' to the gospel meal you may want to serve later.  But in any case, it is the right way to speak.  God sees the way you communicate and what you say.  Does that bring Him joy or grief? (Ephesians 4:30).