Tom,
Ask the guy to save the kml file and mail it to you. He'll probably tell you that you can't save a measurement path in Google Earth, and he'll be right. I just wanted to take this opportunity to whine about the fact that Google STILL has not fixed this deficiency in GE, which is unbelievable.
Anyway, ask him to draw a regular path over his measurement path and save the result and send it to you. Read it into GE and you'll find that one of the following is true (along with a percent likelihood of each):
25% For a fair number of the turns the path he followed is closer to the LPR than the SPR.
25% A fair number of the turns are not visible due to tree or building cover, so it's impossible to tell if the SPR was followed.
25% For some of the turns it is impossible to determine the boundary between road and sidewalk, so it's impossible to tell if the SPR was followed.
25% He started or finished at the wrong spot, or it's impossible to tell exactly where the start and finish should be because they are located relative to something not visible on the map.
99.9% Some combination of the above.
0.1% Your measurement was wrong.
That last percentage might be a little high.
