People spend too much time calculating the risks that come with being honest - and too little time thinking about the rewards. I've been counseling businesspeople for more than 25 years. Only twice have I seen people get fired for speaking their mind. And within a month, they had a promotion and a raise. Most leaders want honest communication - even if the message isn't something they want to hear.
Radical honesty is addictive.
Once people discover the truth, they fall in love with it. That's how human beings operate. People prefer to tell other people what they want to hear. I don't worry very much about whether everything I hear in a meeting or read in an email is the unvarnished truth. I don't need perfect people.