I'm going to tell someone at the bakery that their concealer isn't blended
Why would you tell them? Won't it just upset them?
I don't care to compliment people who are not considerate
You should not try to hurt peoples feelings if you can help it. If you can give constructive advice on how to fix her makeup, then you might want to say that, but just saying it looks bad won't accomplish anything.
I'm going to make fun of their looks.
This is not acceptable behavior, and I hope I can convince you not to treat a stranger this way. You won't gain anything by criticizing someone that you will never see again, and they're just going to be hurt by your harsh words. Since this situation doesn't concern you, I suggest that you just forget about it.