CHARTER FLT WITH FAA INSPECTOR R SEAT HAS ALTDEV.

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WE WERE GIVEN A TRANSITION FROM OLYMPIA ARPT TO THE GREY NDB FOR APCH SEQUENCE INTO TACOMA INDUSTRIAL. WE WERE THEN INSTRUCTED TO HOLD AT THE BEACON AT 4000 FT AND OUR SEQUENCE WAS #2 FOR APCH. WE RECEIVED INSTRUCTIONS TO DSND TO WHAT I UNDERSTOOD TO BE 2000 FT WHICH WAS THE INITIAL APCH ALT; AND READ BACK 2000 FT. UPON REACHING 2400 FT ON AN INBOUND HDG OF 347 WE WERE GIVEN A VECTOR TO 270 AND INSTRUCTIONS TO CLB TO 4000 FT. WE WERE THEN INSTRUCTED TO HOLD AGAIN OVER THE BEACON; AND SHORTLY GIVEN APCH CLRNC TO THE ARPT. I WAS INSTRUCTED TO CALL SEATTLE APCH ONCE ON THE GND. I EXPLAINED TO THE SUPVR THAT THE CTLR SEEMED VERY BUSY; AND COMS WERE POOR. THE CTLR WAS NOT COMING IN REAL CLR OVER MY HEADSETS; AND HE DID NOT CORRECT THE READBACK. THERE WAS AN FAA EXAMINER IN THE COPLT'S SEAT AND HE DID NOT QUESTION THE DSCNT. I WAS TOLD THAT THE CTLR THOUGHT IFR SEPARATION HAD BEEN COMPROMISED BECAUSE OF 2 ACFT AT THE SAME ALT AND A RPT WOULD BE FILED. THE AREA WAS VERY BUSY WITH 3 ARPTS WITHIN 5 MI OF EACH OTHER; AND A RESTR AREA WHICH WAS ACTIVE. OTHER CONTRIBUTING FACTORS: FATIGUE FROM LONG FLT AND POOR COMS CONTRIBUTED TO WRONG PERCEPTION. I WAS LOOKING AT THE APCH PLATE WHEN INSTRUCTED TO DSND. THE INITIAL APCH ALT WAS 2000 FT. CORRECTIVE ACTIONS: CTLR LOAD SEEMED TO BE TOO MUCH. AN EASING OF WORKLOAD COULD HAVE CAUGHT THE ACFT DSNDING THROUGH ASSIGNED ALT SOONER. THE EXAMINER IS THERE FOR SEVERAL REASONS; ONE IS TO ENSURE THAT THE PLT'S ACTIONS ARE SAFE; AND WHEN IN DOUBT I SHOULD HAVE REQUESTED CLARIFICATION FROM THE CTLR.