On Aug 8, 2017, at 11:46, Eli Zaretskii <eliz@gnu.org> wrote:

Is it a GUI session or a TTY session?

It's a (Cocoa) GUI session that is broken, and looks bad even with I start with -q or -Q, so whatever it is doesn't seem to be related to any configuration I have.  (The only thing I did between working and not-working was upgrade the OS.)

TTY sessions still work correctly.  (Indeed, that's how I'm coping!)

Also, what do you see in a buffer popped up by "M-x list-colors-display"?

I see a list of colors that appear reasonable.  I've attached an image of what things look like; you can see the dark fringes and the black-on-black mode line too.