I've had my cat to the vet on 2 separate occasions recently for "stomach issues" and a horrid smell coming from her mouth. The vet missed it the first time, but caught it yesterday.
Evidently, when I was putting away some leftover floss, I dropped some and didn't notice it. Well, Renata found it and had one strand wrapped around her tongue and a pretty good sized wad stuck in the back of her mouth where the whole area had become infected. Luckily, it was an easy removal and the cat is fine. I just have to be careful in the future.