You really do have a reason to clean primer pockets, you may not realize it but anybody that reloads for a Garand or an M1A absolutely needs to clean their primer pockets to help reduce the chances of a slamfire.
When the primer pockets fill with fouling the primer will not seat to it's proper depth, it will sit higher than it should. The Garand and the M1A use free-floating firing pins, when the bolt goes in to battery the safety bridge is the only thing that prevents the firing pin from impacting the primer with enough force to ignite it (it slows the bolt down and reduces the momentum of the firing pin). Chamber a fresh round and then eject it without firing it, most Garands and M1As will produce a slight impact on the primer just from chambering the round, it's no big deal as long as everything is in good condition because the firing pin doesn't hit with enough force to ignite the primer until you release the hammer. But as the rifle ages and the metal wears the dimensions and features of the safety bridge can wear enough that the firing pin can move forward with greater force than is safe and if the primer isn't seated deep enough it becomes easier for a slamfire occur. These rifles require that the primer face be around .007" below the surface of the case head for best operating conditions.
A lot of people think that slamfires aren't dangerous but that's because most people don't know what a real slamfire is and they think that the cartridge will just go off unexpectedly while it's in the chamber. While that can happen with a slamfire it's also possible for a cartridge to ignite before the bolt has gone in to full battery and then the case will rupture and shrapnel and hot gasses (and possibly rifle parts) will eject from the rifle within a couple of inches of the shooter's eye. Here's an example of an out-of-battery detonation, it could have been from a slamfire or it could have been due to other reasons but in either case it's still an out-of-battery detonation and it gives you an idea of what it could be like (and the lady is firing a Garand)