That's a bit of a loaded question...but I'll answer it as best I can.
In my experience, when someone says, "I'm just being honest," the translation reads, "I'm about to be absolutely brutal." Except, of course, when it's a used car salesman, in which case all bets are off.
In one of the books explaining the tenets of the spiritual path I follow, there is a principle mentioned which pretty much tracks the old saying, "If you can't say something nice, don't say anything at all." In our case, it's formed as a triple question:
1. Ist it TRUE?
2. Is it NECESSARY?
3. Is it KIND?
And if it's not ALL THREE...silence is golden.
Now, that's a bit of a head-scratcher when you run up against something that's both true and necessary but definitely not kind. But there it is. So far (these past 38 years and some months), the principle has worked for me. On my better days, I even break it down in my thoughts to an acronym: TNK. Short for THINK, and also TRUE? NECESSARY? KIND?
However--not to duck your question or give it a politician's dance-around--you asked about lying, not simply being silent. Obviously, a lie flies in the face of the "Is it TRUE" portion of TNK...but there ARE times I will lie like a rug in less than a heartbeat, take whatever karma comes with that, and never flinch.
As en example, let's say I had the misfortune to be present when the Connecticutt shooting went down, could do nothing about it, but saw how a number of the victims died. The images are (in this thankfully not-true example) in my head forever. A parent of one of the deceased little ones comes up to me and asks if I saw how her child went? She needs to KNOW, she says, I MUST tell her.
No. I must not. I am neither a cop nor a reporter nor the medical examiner who had to do all the autopsies and report the findings. I am, instead, the only survivor from the room where her child died, racked with survivor's guilt and burdened with nightmares for the rest of my life...AND I WILL LIE.
I will tell her, "I didn't see. All I know was, it was fast." If I have to, I'll make up a story about getting knocked out, SOMETHING, but I will not add to her burden in that way.
Okay. That's an extreme example. But one thing of which I'm certain: There is such a thing as too much honesty.