I agree, Shirley, a reader should inform a writer if the former observes a typo in the letter’s article. And do so in a low-key way, to avoid embarrassing them. I like your idea of suggesting the writer has spinach in their teeth. I tell the writer they have toilet paper stuck to their shoe. Or a Q-Tip sticking out of their ear. I once told a writer they had a tampon string hanging from their - well, never mind. That proved to be awkward. Mainly because they actually did have a tampon string hanging from there.