I had an argument about this with an FAA inspector once. I was at the time flying with a guy who had a twin on a 135 certificate. He frequently had charters which meant empty legs. While inspecting my logbook for my 135 pic checkout for the same company the FAA examiner, who was also the 135 POI , saw that I had logged around 9 months of PIC time in the aircraft. He berated me for padding my logbook and doing it illegally. His argument was that I was not checked out for the 135 and that passengers pay for the empty legs. My argument was that the airplane is not operated under the 135 certificate but was being operated part 91 and I was appropriately trained and rated to fly those flights and the passengers did not know or pay for whether the airplane was being relocated 1o0 miles back to the aircrafts base or 1000 miles anywhere else.

This was the one and only time in my 13 years in aviation that I won an argument with the FAA.