ALL SHOCK ENDS HAVE SPHERICAL BEARINGS WHICH ALLOW YOUR SHOCK TO MOVE AND ROTATE DURING THE SUSPENSIONS MOTION. 
PERIODICALLY CLEANING AND GREASING YOUR SPHERICAL BEARINGS IS A GOOD THING TO PROLONG THE LIFE OF YOUR SPHERICAL BEARINGS. 
HOWEVER MUD, CRUD, SAND AND GRIT AS WELL AS LACK OF MAINTENANCE WILL ALLOW BEARINGS TO WEAR OUT. 
IN THESE CASES SPHERICAL BEARINGS ARE AVAILABLE AND CAN EASILY BE REPLACED AND ARE CONSIDERED A WEAR ITEM.