For about the billionth time today, I read a complaint about the use of the phrase "to be honest" in everyday speech. The complaint is always the same: "'To be honest' is a useless phrase, unless you're normally in the habit of being dishonest."
Correct in theory, wrong in practice.
In practice, "to be honest" is used in contexts in which the truth is normally avoided because it is considered too hurtful. By prefacing the truth with the phrase "to be honest," you are saying, in effect, "Okay, brace yourself...", or, "All right, you asked for it..." It's a way of saying to the listener, "I'm not a heartless son of a bitch. I know that what I'm about to say might hurt you, but I think it's important for you to know the truth."
For example, about 10 years ago a woman I had been dating--someone I liked very much--told me she didn't want to see me any more. I asked her why. She gave me some claptrap about how busy she was with work, how the timing was all wrong, etc. I said, "Please. Those are things you say when you don't want to hurt someone's feelings. I'm a big boy. I can take it. So why don't you tell me what's really going on?" Her response: "Okay, to be honest..."
She was saying, "All right. I'm going to be honest in a situation in which it would be easier for both of us if I were dishonest. But you asked for honesty, so I'm going to give it to you."
In that context--which is the context in which it is normally used--"to be honest" serves a very useful social function.
Footnote: Regular readers may recall a similar post on the use of the word "obviously." The standard complaint about "obviously" is that if something is obvious, you don't need to point out that it's obvious. Everyone recognizes its obviousness by virtue of the definition of "obvious."
I believe, however, that "obviously" is appropriate in contexts in which you want the listener to understand that YOU know something is obvious. Why? Because if you say the obvious thing without flagging it with an "Obviously...", your listener might think, "Geez, doesn't he know that's obvious?" For example, if I say, "This was a disappointing season for the New York Yankees," your average sports bar lunkhead will say, "OBVIOUSLY, Einstein." But if I say, "Obviously, this was a disappointing season for the New York Yankees," sports bar lunkhead will say, "You ain't kiddin', boss."