It isn't very high on my list of annoyances, but I was reading an article by somoene who doesn't know the difference between loath and loathe.
They look similar. They sound similar. But the meaning is as different as disinterested is from uninterested.
Loathe is a verb, a bit stronger than hate. I loathe boiled carrots.
Loath is an adjective, meaning "unwilling". I am loath to go out in the rain.
Loth is an alternative spelling of loath.
So now you know why, at that point in the article, I was loath to read on.
You can see the same thing with:
bath and bathe
breath and breathe
cloth and clothe