The idea of "good" is highly subjective. Of course gun owners (myself included) would believe that someone who owns an instrument that has the ability to take life is responsible, intelligent, just, would be definitively and demonstrably good. However like anything when pushed to its limit, goodness can have its own fatigue where a person can incorrectly judge a situation where use of deadly force which originally thought was necessary became unnecessary. I take into account the recent example of Michael Drejka who was recently convicted of killing a man over a handicap spot. His argument of course was the stand your ground law, because he felt he was in imminent danger. Viewing the video footage, jurors saw after Drejka was pushed to the ground, the victim step back after Drejka displayed the weapon indicating that he was not advancing and therefore not a threat, but the victim was still shot and ultimately died in front of his son and girlfriend (see
source).
I take also another example of a man by the name of George Meyer who pulled his gun in a Church by the name of Grace Christian Academy who did so under the pretense to show the martial arts instructor that martial arts isn't necessary when one has a weapon in a confrontation. So, to demonstrate that Meyer pulls out his gun and says "bang you're dead." In his defense Meyer claims to not have pointed the weapon, only to demonstrate his position regarding the argument (see
source).
Most certainly all of us who respond to mass shootings wish that there was some reconditioning of gun legislations, some on the other side believe that there ought to be more people with weapons to defend against mass shootings. As @ChristineM (or @Saint Frankenstein maybe??) once said in a discussion "if everyone had a weapon then how could police discern between friendly and villian? It would appear that having more guns is not the solution to our modern problem involving mass shootings. What I'm more concerned about is the individual who believes guns and not diplomacy is the answer. I'm concerned about the drunkard who is carrying a concealed weapon legally who gets into an argument and decides to use his weapon. I'm concerned about the racist who hates this or that culture and decides to pull out his weapon because he cannot stand the sound of rap lyrics.
I'm concerned about these so-called pretentious good guys who are lawfully carrying weapons but do not exercise good judgment. I'm also concerned with the idea that the "good guy" argument is not allocated to everyone. When people of color carry weapons it is a problem as we saw in the banning of assault weapons (called the Mulford Act) in California's capital of Sacramento. It wasn't banned because assault weapons caused deaths it was banned because of the Black Panthers exercising their second amendment rights (see source). Or when a good guy like the security officer stopping a criminal but happened to be carrying a weapon himself, shot and killed by a police officer (see source).
I firmly believe the idea of 'good guy' fails because we don't know every single person walking on this earth nor their intentions. I understand we wont be able to prevent mass shootings or criminal activity involving guns, but what we don't need are people being judge, jury, and executioner in these streets.