@alex only as a checksum, not as something which has to be copy/pasted or typed out, since that isn't reliable.
You could use both emoji and ascii and buttom to switch them, or automatically translate between the two, or keep emoji as a display, only revealing the ascii when it needs to be copied or entered somewhere.
I really like the idea though, there is a lot of research that shows that humans are much better at seeing small details in human expressions than anything else.