This. I have a couple of friends who know they are bad spellers, know they sometimes use the wrong word, or when speaking, pronounce things wrong. I correct them, but not in public. Usually they thank me.
I always spell words correctly, and use the correct word when replying to someone who has made an error. I cannot imagine using the wrong spelling or word to avoid possibly hurting someone’s feelings.
He’s your friend so all the more you should correct him.
Ha! Look whose avatar is talking!
This is what I do with my sister, the bad speller. I also tease her about it when the subject comes up. 
This, except when the misspelled word is my name. Any friend who misspells my name when not replying to a letter by me gets a pass, any friend who misspells my name when replying to a letter which has my name both in From: and in the signature gets wet-trouted.
Huh, why would you misspel something on purpose to protect someone’s feelings? Like the Queen drinking from the finger bowl?
Nah, I won’t say anything unless I know for a fact that they’d appreciate it, but I’m not going to misspell things on purpose. How else will they learn?
Annoyingly it has happened to me on several occasions that people have miscorrected my spelling. For some reason it’s always the Dutch word “sowieso” that does it. It means “in any case” or “anyway”, and nobody can spell it. I’ve seen “zoiezo” and “zo wie zo” and all sorts of variations. I send something back that happens to contain the correct spelling, only to get a reply telling me I misspelled “sowieso”. :rolleyes: For that, no holds barred. You are going to get told you are a moron, with references.
Not quite the same, but I have a friend that will correct your pronunciation of Japanese words.
Me and my friends are middle-aged anime fans, not actual Japanese people or current Japanese language students.
I’ve increasingly found this irritating to the point of wanting to smack her. 
I would think fans would care about getting it right. Isn’t she saving you from looking foolish with actual-Japanese or knowledgeable folks?
Around here, that’s called Gaudere’s Law, but I recently learned the much more universal name for it: Murhpy’s Law.
Many people have asked me to correct their spelling and punctuation, and I will; otherwise, I do as others have suggested, and use the correct spelling in a return letter or post. If the person picks up on what I hope is a tactful correction, that’s good; if not, I think I’ve done my part without being rude.
On a tangent here, I do appreciate it when someone suggests that I have used the wrong (generally spoken) word and offers a better one.
I was at the dealership the other day and was using the word “gaskets” instead of the proper “weatherstripping.” The first Service Writer let it go (no harm there) but the second Service Writer corrected me and I did appreciate that.
I love this thread. It’s a laugh a minute.
Keep it coming!
Old joke: There’s one word in the dictionary that’s always misspelled… can you name it?
Misspelled?
Yes. 
You misspelled ‘no’.
Ahem. “Know.”
If they’re generally sharp, or generally a good speller, then yes, correct them, subtly. If they’re not, then don’t waste your time.
It’s rude to correct someone’s spelling, grammar, etc unless; they ask you too, or you have some kind of supervisory relationship (ie your their teacher/tutor/boss/etc).
Cite?