All parts that hold bearings loosen in the direction the bearings rotate under load.
Drive side crank arm spins clockwise under load therefore drive side cup comes off clockwise.
Left pedal's bearings spin clockwise under load therefore left bearing unscrews clockwise.
Exception: Items that require lockrings. For example cones on hubs tend to be naturally threaded (unscrew is counter clockwise)... This is actually more due to the fact that these are using compression to hold the assembly together and the locknut keeps the cone from moving.
Note: this is the rule and there are some exceptions in older bikes.