This is an unusual, but interesting dog tip. The palate of a pure bred dog's mouth is one solid color from the very front of it's mouth to all the way to the back of it's throat, where a mixed breed isn't. Over the years I've looked at my friends' dogs' palates, both purebred and mixed, and found it sort of amazing.
I witnessed this several years ago at an Obedience Trial when this one lady said her dog was a Labrador Retriever and that she had papers on the dog. One look at the dog told the judges and spectators that the lady's dog was not a full blooded Labrador and she argued with the Ring Judge over it. I felt bad for the dog, the lady made a huge stink over it causing a small scene until the judge asked three different Labrador owners and their dogs into the ring and inspected the palate of all 4 dogs, with their owners. She wasn't permitted to show and still argued with the judge and was finally asked to leave the premises. Keep in mind that this was many, many years ago. Last year the AKC ruled that a mixed breed dog can be shown in Obedience as long as it is spayed or neutered.
By CPJ from Madison, AL