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

Horses teeth wear as they age, so by “looking the horse in the mouth” you’re checking out its age and value. The expression saying not to do this is saying how rude/uncouth/ unappreciative you are to do this in front of the gift giver.