
Many years ago our first homebred Champion was X-rayed, and the vet advised us not to send the plates in as they didn't look good, in their opinion. Like Maddog, we felt that it was wrong to skew the average for the breed as a whole, so we sent them in anyway. The plates came back with a total score of 8, well beneath the breed average.
I wouldn't trust the opinion of anyone other than the specialists that actually do the scoring. Some vets might know what they're looking for on the plates, but equally some don't.