Simple typos or common misspellings are not much fun to point out.

It gets interesting if the incorrect spelling either creates something unintentionally funny, or reveals a writer’s lack of preparation or ignorance. These generally are not grammatically wrong and might not be caught by a proofreader.

I’m pointing this out because just the other day, in a book about WW II, I came across a reference to the 1942 St. Nazaire Raid in which the British destroyer involved was repeatedly mentioned as “HMS Cambletown”. Now that is indeed how you pronounce it. However, it is spelled “Campbeltown”, thus revealing the author as a superficial phonetic speller who apparently didn’t bother to actually read up on it, but heard about it somehow.