When I recieve a clearance I don't intentionally record it incorrectly. I repeat it back fully expecting to be told "read back correct" Unfortunately from time to time I am corrected on something. Point being that even routine clearances can be hacked up. I suggest pilots always read back the clearance. I also recognize that controllers may not catch errors in the readback, but then again they might. I also recognize there is a finite number of clearances that can be read in a given period of time. That number of course would increase with a "roger" in lieu of a full readback. I have waited 10 minutes plus at LAX awaiting a clearance. That is the price for the additional level of safety a readback provides. Those mistakes will start to be caught by departure or center guys as we blow through an altitude that might have been caught by the CD controller