Sort of.
In our current campaign we're low level. My character prefers non-lethal solutions. Being low level, I'm presuming that he isn't yet the hardened, casual killer that most players seem to run.
Several times, when we face an implacable opponent (one who attacks on sight and can't be reasoned with), my character will bandage their people-type fallen after the fight (after ours are handled, of course.)
Aside from the fact that he occasionally loses his lunch after we're forced to kill, he figures that we might be better received should we ever have to come back this way.
In short, I'm running a civilian, with a civilized upbringing, for whom casually killing opponents will never sit well.
******
In a 4e game I was DMing I had the party meet a Tiefling lady who claimed to be a simple cook. The party proceeded to not-very-casually question her about her combat skills, a conversation that culminated in one of them finally asking her bluntly, "How do you kill people?".
She was shocked, and asked, "What kind of person do you think I am?"
Then it was their turn to be shocked: She really was an NPC, a commoner who wanted nothing to do with war or killing, and who had a commoner's view of, well, murder.
Taking life is such a casual thing for most PCs that I thought I would remind them that, to most civilians, the line between being a Player character and a serial killer was very very thin.