But no, that's silly. Really, you just need to give up on the idea of being anonymous in public. Because that was never something that you could count on.
I have noticed that it's very hard to recognize faces of people with very black skin, under low-light conditions. So I can imagine black makeup that's 100% non-reflective across a wide range of wavelengths. But then there's millimeter-wave radar. How would one block reflection of mmW radar?
I know this is crudely put and thus being downvoted, but there is a kernel of truth to it similar to the XKCD encyption / wrench[0] comic. Sure, you might've beat facial recognition in the lab, but in a real world scenario you're walking around in ridiculous looking clown face paint so you're going to come under immediate scrutiny regardless.
[0] - https://xkcd.com/538/