The implication of the phrase “to be honest” is that when you don’t say it, your statement is a lie. And the sad thing is, this is probably true.
The Cynic philosopher Diogenes is said to have walked through the streets of Athens, waving a lamp in broad daylight, proclaiming he was looking for an honest man. Apparently he never found such a man in Athens, and when we hear this, we’re not surprised.
ADJ 