

That presupposes though that a shapeshifter would need to see their own reflection to judge the look. If you have developed over millennia the ability to change your appearance at a molecular level, or physically speaking thereabouts, you probably have developed the ability to judge the look without having to look at it. You would be a rock who knew how to become Michelangelo’s David.
I’d be amazed to hear that chameleons practice at a puddle before they try to blend in with the jungle. But I was sick a lot when they taught biology in school.
In their defense, they were probably lying before the advent of so-called AI as well.