PRIOR TO THE FLIGHT N70531 WAS NOTED TO HAVE THE ENTIRE CABIN AREA FULL OF CARDBOARD FISH PACKING BOXES AND EMPTY 5 GAL BUCKETS STUFFED ONE INSIDE THE OTHER. THE ACFT WAS NOTED TO BE HEAVIER THAN NORMAL DURING REPOSITIONING OPERATIONS. THE PLT STATED DURING A FLT WITH ANOTHER PLT THAT HE DID NOT HAVE A LICENSE AND HE DID NOT NEED ONE. WITNESSES OBSVD N70531 MAKE 3 TKOF ATMPTS FM THE LAKE HOOD SEAPLANE BASE AND NEVER GET UP ON 'STEP'. ON THE THIRD ATMPT AFT PORPOISING AND USING A CONSIDERABLE DISTANCE FOR TKOF RUN THE ACFT LIFTED OFF THE WATER JUST CLEARING A BLDG AT THE END OF THE LAKE. WITNESSES ALSO STATED THAT THEY COULD NOT SEE THROUGH THE WINDOWS OF THE ACFT DUE TO CARGO. THE ACFT WAS NOTED TO CLIMB TO ABOUT 200 FEET, LEVEL OFF, THEN DESCEND INTO UTILITY PWR LINES AND A BUILDING IN A NOSE HIGH ATTITUDE. REMOVAL OF THE FUEL CONTROL FILTER REVEALED DIRT AND DEBRIS WHICH ALMOST COMPLETELY OBSTRUCTED THE FILTER. THE TOX RPT INDICATED COCAINE IN BOTH THE PLT'S AND THE PAX'S BLOOD.