What are the objects in each corner of the image?
Some of our images are taken in our photo booth with the camera suspended above the item, so those have no objects in the corners. One exception to this is when photographing magazines (or stills that are "curled"), we may use magnets as weights to hold the magazine open (or to keep the stills from curling) while photographing them, because they will not lay flat otherwise.
Most of our images are photographed on our two black metal walls (these images have a solid black background around the edges), and they are held in place with magnets so we do not have to attach the poster to the wall in any way! These magnets have square heads and look like small squares in each corner of our image (they may also be round magnets). If our image has squares in each corner, know that they are magnets that are temporarily holding it in place, and are NOT any kind of defect!
If any objects in the corners of any items we auction are NOT magnets and are actual defects, we would describe that in words in the condition description.