First of all is the brass from a rifle or handgun? Second, is it from your gun or range pickups? If it's from your gun you need to determine why the ejector is hitting the brass hard enough to mark it. You may need to go with a stiffer recoil spring or lighter load to lessen the impact of the case on the ejector.
Generally speaking the extractor or ejector are not going to affect the structural integrity of a brass case. However, they may deform the case head enough to give you chambering problems. A simple way to determine whether they have deformed the case head is to buy a cartridge headspace gauge. If the case doesn't drop freely and fully into the gauge then it's dimensions are out of spec and it should probably be scrapped as it's going to give you chambering problems. If it's a handgun a cheaper (but slightly less precise) way to do this is to take the barrel out of the gun & drop the cases into the barrel. If case dimensions are in spec the rear of the case will line up with the rear of the barrel. Drop in a brand new case to see where it lines up & you'll know what I'm talking about.
As others have noted, if the primer pocket is loose the case is scrap. However, if the pocket is snug and the case chambers fully in a headspace gauge then the case should be good to go.