None of my kitties ever were very interested in mirrors. I think that they knew what was in there, because the first time seeing one they'd study it, only with their eyes, for maybe a few minutes, maybe sniff it, then walk off, going "Ehh, so it's my reflection, so what?"
Or at least that was the message that I got from them.

They also know the concept of how glass reflects, and whenever I shine the lazer light in the mirror, they automatically look in the opposite direction for the light on the other side of the room!

Though Clover likes to examine the pictures I take of her. I swear, she's thinking, "That's not a very good picture of me, I look fat, but Oh! Here I look nice! Keep this one!"

Either Echo just doesn't care how she looks, or she doesn't have a very big self-image, but she just ignores mirrors for the most part, and won't even look at the pictures I take of her.