Light On Dark Water

I've always thought that it's slightly odd to open a sentence with "To be honest." The implication is that being honest is a departure from your usual practice. Yes, of course, I understand that it means you're telling the other person something he or she may not want to hear, and which in the normal course of things you would refrain from saying, but which you feel is called for in the present situation. For the other person's good, of course. Perhaps you're listening to someone complaining that his or her spouse complains about a certain habit of his or hers.

"She says the way I harangue people about politics is obnoxious."

"Well, to be honest, you do sometimes come across as a little harsh to those who disagree."

Many years ago I saw a cartoon which used that device, popular among cartoonists, which I guess owes something to Sigmund Freud: a man lying on a couch speaking to a psychiatrist. In this one the patient is saying "I said people seem to dislike me for some reason. Open your ears, fathead."

That fellow could have used a friend willing to be honest about his manners, though very likely the friend would have suffered for it.

Then there's "If I'm being honest…" More or less the same thing, but it carries a stronger implication that honesty is not the speaker's normal mode. 

And then there's one I don't recall hearing until sometime in the fairly recent past: "If I'm honest…" As far as the intention of the phrase is concerned, it's not substantially different from the other two. Maybe. But to my ears it suggests doubt about the person's basic integrity. It's not about the specific conversation; it's about the person's fundamental character: well, are you honest? It invites the listener to speculate as to whether the speaker is, at heart, honest or dishonest, and to consider whether or not what follows should be believed or not. 

I know, I'm taking this too literally. But my liking for precision in language has only gotten stronger as I have gotten older. To be honest.