When asked about where I wanted to be in my career by my boss (boss' boss actually), I was honest about having my resume out there and looking for other opportunities outside my current company. Now, I've heard from other sources a promotion that was possible in my future has been basically pulled.
Honesty is not a good policy. Keep lying.
Everyone says they want the truth, but if you are told you're not doing meaningful work, the justification for your job is vanity metrics, and the guy with less experience than you who does terrible work makes more money than you, how happy would you be?
If you told management, you're using the position and any promotion as a jumping off area for a newer better job at a different company, how happy would management be?
Pleasant loyalty is a good way to stay employed when you're doing a mediocre job.
So I like being ruthlessly honest about this stuff. I'm much much happier this way than I have been in the past where my relationship with my employer involved more charades around future plans.