Carbon is incredibly honest material. It’s best to compare to an egg. It’s primary function is to hold shape under high pressure. It doesn’t like hard or focussed objects on one point otherwise, like an egg, it will fracture and you will know about it!
If you have had a crash and you are wondering whether the bike is ok, simply look for signs of paint cracking. It is not common for carbon to crack under the paint without it showing somewhere, however it can travel under the paint from a fracture.
If you have had a graze and the carbon is showing bare, press to see if there is any movement or get it checked out. Don’t leave it bare!
I will address the issue of bike paint in my next rant…