May I recommend Lucky Jim by Kingsley Amis if you can get hold of a copy. There’s a very funny description of how the hero wakes up after having emptied his boss’s liquor cabinet the evening before. Among other things “a little creature of the night had used his mouth first as a latrine and then as a mausoleum. He didn’t feel good”.
I had a tooth abscess once that ruptured. Those are supposed to smell extremely awful but I didn’t notice anything. Usually things crawl up one’s ass to die but some furry creatures may not have gotten the memo.
I’ve found that if I brush or use mouthwash before going to bed, my morning breath is much more palatable. It’s not smelling like roses or anything, but its not as stanki-fied.