"lying to the plebs modifies their behavior very slightly in a good way or is it in a bad way?"
It's irrelevant, treat your fellow humans with some modicum of respect and dignity. Terry Pratchett's first rule of morality "don't treat people as if they're objects".
Anyone caught casually deceiving people for some tiny perceived benefit to either themselves or the people deserves a severe lesson in how "irrationally" angry people get when they're lied to.
You can save this page and the comments as an example to future generations of how the elites of this century had become morally bankrupt.