[pianotech] justify pitch raise

[Leslie Bartlett]

I tuned for a first time customer today,a  piano teacher who said her 
Kawai G3 had been regularly tuned (6-months) for years, and then missed 
a year because the technician retired.  Unfortunately the piano was a 
disaster. In Tunelab I could save all the overpull measurements and show 
the lady (a masters degreed teacher) each note and it's relation to "0 
cents".  Seeing the mess, she understood immediately because she had a 
visual reference to justify my contention.  But she was in agreement 
that had I just walked in,and said "you need to pay me for a pitch 
raise", she would have been less than sympathetic.

My question is "How do the strictly aural tuners justify or "prove" a 
need for serious pitch raise, convincing people of the veracity of the 
claim?"  It seems with no measurable reference which provides some kind 
of proof other than opinion, could be very problematic.   Opinions 
please. Thanks
les bartlett