Dont know whether I would call it the best trial lesson but certainly one of the most interesting.
The local commercial radio station rang me up to say they were doing research for a programme and did I remember doing a trial lesson with "Fred Bloggs" a couple of years ago. Got the logbook out and yes there he was on the date in question.
After some discussion I suddenly recalled that after the trial lesson I asked the "student" where he had flown before because he was the most natural pilot I had ever taken on a trial lesson. He swore blind that he had NEVER been airborne before much to my consternation.
The man from the radio station then came clean and said there were doing a programme on regressing subjects to previous lives under hypnosis and the student had been a World War II fighter ace in a previous life!!