Voters tend to prefer honest politicians, all else equal.
To quote the Sun Tzu, "War is deception." The goal is not to be ethical or moral when dealing with the enemy.
Lying is not an admirable quality in a teacher, nor a sign of competence.
We could get into the benefits vs detriments of the Santa Claus and Easter Bunny myths on society, especially kids, but that's for a different thread. Different site, even.
Even so-called white lies can be problematic.
The priest isn't lying if he genuinely believes what he preaches. If he doesn't so believe, he's doing his parishioners a disservice by remaining in the priesthood.
A large portion of society would consider the average police officer to be neither moral nor ethical.
Like I said, most reasonable people would consider lying to be neither moral nor ethical. I'm not suggesting that lying isn't commonplace, just that that doesn't make it morally or ethically acceptable.