And how distraught is Tony Stark that his weapons are being used by terrorists in the first Iron Man? Triple-distraught, because when he sees his own reflection, he shoots down three glass windows.
What truly cranks the profundity up to 11, though, is whenever a character looks at themselves in the shattered glass. Naturally, their reflection is all sorts of screwed up, because, like, so is their soul. Right before Brandon Lee assumes his avenging vigilante identity in The Crow, he smashes his mirror ... and probably feels rather dumb right away, because he's gonna need it to put on his Juggalo makeup.
Sometimes they don't even have to hit the mirror to break it. In Carrie (2013), Carrie is struggling with the realization that she's clearly Carrie from the movie Carrie (1976), so she telekinetically breaks a mirror and looks at her messed-up reflection -- just like the other Carrie did. John Travolta does something similar in Phenomenon.