Unless the players characters exist in a vacuum, their actions are going to have effects on their surroundings beyond a trail of dead goblins. Every action they take will eventually be noticed by someone and a reputation will build around the characters. How quickly that reputation will build depends on the media technology of the setting, but it will grow. I’ve previously talked about heroic fame and the opportunities arising from that. Of grittier tone is the concept of player character infamy.
Infamy or to be infamous. A person having carried out an act that is regarded by the wider world as wrong. How this will affect both character and setting depend on the reasons behind the act. It could be that the hero was faced with a hard choice. Do they destroy the space station now to prevent breach of quarantine or give the medics more time? Murder the child now to prevent it from becoming a monster when an adult? People will understand, logically, that you made the right choice but they will still shun a person they believe to be unfeeling. If the player had more information available to them than society, then they must suffer the consequences of burning down a school full of vampire teens. In these, a character can in some way hold their head high, with the self belief that they made the right choice.
Deliberate crimes present a different challenge, though a rarer one. Many of us are happy to play as criminals, up to no good for various backstory reasons. Few of us are going to enjoy a game where we play a group of serial killers murdering their way a city of innocents. In both cases, the character is infamous, but the use of that infamy is curtailed. A social aspect, infamy only engages with the storytelling when the NPC knows who they are talking to. In the criminal scenario a core part of the game is making sure people don’t know who you are, else the authorities put a stop to your ways.
As a storyteller, if I have a device available to me, I want to be able to use it. Which leads me to the final point, the effect the infamy has on the infamous. Some might revel in it and use their trail of blood to intimidate others. The more interesting story is that of remorse. A character who seeks redemption for past deeds is a common trope because it is emotionally powerful. It gives both player and GM a strong foundation to build the character’s personality and motivations, which can only enrich the story telling.
But as long as not everyone is doing it. Nobody wants an entire party of brooding anti-heroes…