It's like people forget Mimane is a mirror. When their use is kept to its most simple purpose, they reflect the truth. Mimane is a prime example of this. Mirrors can be used to misdrect, to lie, but Mimane never lies on her own. She only does it when asked to. Left to her own devices, she always tells the truth, just like her mirror form.
Mimane, were you peeping on us?
Yeah.
She seems simple, but she's not. I think for her the truth is a lot more fun. Why waste time dressing things up to spare feelings, or use passive aggressive language to get what you want. Just show people the truth, and don't deny your own flaws. Just like a mirror.