Real locks have a wide range of mechanical features and defects that help and hinder lock picking.
If a lock doesn't respond to scrubbing, then it probably has one of the traits discussed in this chapter. To open the lock, you must diagnose the trait and apply the recommended technique. The exercises will help you develop the mechanical sensitivity and dexterity necessary to recognize and exploit the different traits. It can be very frustrating to spend a long time picking a lock and then discover that you turned the plug the wrong way. Section 9.11 also explains how to turn the plug more than 180 degrees if that is necessary to fully retract the bolt.