A young woman is standing at the bottom of a staircase with her foot on the bottom step. She is looking up and smiling at something that is blocked from my view by the neighboring house. There is a slightly indulgent quality to her smile that makes me think she is looking at someone very young or very old.
I pass the obstructing wall and see that she is looking at a cat. Or, more specifically, she is looking at a woman who is a few years older than herself who has a fat cat on a leash. I smile at the women as I pass because I am looking right at them and it is the neighborly thing to do. The younger woman continues to smirk at the cat and the older woman smiles back at me raising her eyebrows in a manner I interpret to mean, "Hey look! I have a cat on a leash! Zany, right?"
For me cats on leashes are in the same general category as birds on shoulders or snakes draped around necks. This kind of pet as prop behavior says much more about the owner than the animal. And, frankly, what it says isn't particularly flattering. (You, with the dog in the baby bjorn. Yeah. You too.)
I keep my smile neutral, offering neither affirmation nor denial of the zaniness of a cat on a leash. I try, in fact, to exclude the cat from my gaze altogether. What cat? What leash? Pleasant evening, is it not? That is the neighborly thing to do.