My dog smiles a lot now. When I first adopted her in July, she was 3 yrs. old and had been neglected and abused.
After being with us for a few weeks, I noticed her tail was wagging most of the time, and she started smiling when we spoke to her in a happy, excited way. Especially if we were saying "oh Scout is SUCH a good girl!" Or if we got out the b-a-l-l !