Bumping this thread for a related question.

I noticed today that my favorite helmet has dings and scrapes on the outside of it - primarily on the back and the styrofoam on the side. I haven't hit my head, but sometimes it falls in the apartment, or off of my trunk.

At what point is it too much and it needs replacement? There doesn't seem to be a single opinion on this - and perhaps the fact that I am asking the question answers it for me. Curious to hear what others have to say on this.