Tom - I agree with (and like) the idea of courses having an "ambassador" play with a rater to help them understand the course and its features. But, this doesn't help the situation when a rater is playing as a paying guest at a public course or a companion of a friend or member.
I think most raters understand the underlying differences in conditioning for courses in their home regions, but I'm not so sure they understand courses that are outside their usual sampling. For example, players who visit the South from the Northeast or Midwest often don't understand the different seasons of Bermuda grass and how it affects the playability of the course.
In my example, the guys I hosted were not really on a rating trip. They just wanted to play some golf. But, first impressions are first impressions... and, they were left a bit disappointed in the conditions they experienced... very playable, but somewhat scruffy. But, when your home course is under a few feet of snow scruffy is OK, I think!
It was later when they had a discussion about turning in a rating on one of the courses that I raised an eyebrow. There is no way they could have gotten the full "flavor" of the course, but I guess they didn't want to miss the opportunity to turn in a rating on a course they might never see again. Sort of a Catch 22, I guess.