Beauty is only skin deep. Ugly goes clear to the bone.
Or the brisket.
I've seen several versions of this, but all attributed to Winston Churchill, and I have seen clips of people who were there at the time recounting this story as being true. At a reception in London in the 30s the following exchange took place:
Wife of prominent politician to Winston Churchill (with distain in her voice): Mr. Churchill, you are drunk!
Mr. Churchill: Yes, madam, and you are ugly. But in the morning, I will be sober, and you will still be ugly.