Not to look at gift horse in the mouth

Question

I understand the meaning of the saying and the context it’s used in.

What I don’t understand is why you would look a horse (or gift horse) in the MOUTH. What is special about its mouth?

In: Other

Answer 1

So examining the mouth and teeth of a horse, is a way to gauge it’s overall health and age, and prior to buying a horse, it’s usually a good idea to do. The saying then implies that it would be rude or unnecessary to check up on something that was free to you, I.E. a horse that was gifted to you.