This is a defect of American comics and applies to early Silver Age Marvel comics (mostly late 50s/early 60s). In the process of guillotining the right hand edge, particularly the top copies in a pile, little chips would be pulled out of that edge. Sometimes it can be a slight cracking at the edge that has weakened the paper so a chip is in danger of falling out. In other cases the chipping can be quite severe and this seriously devalues the comic, probably by two grades at least.