Since I got my MBP 2 years ago, I've found some really strange misspellings that the system's autocorrect will change correct words to.
The latest of these is "Ulbrichbt", which OS X unhelpfully corrects "Ulbricht" to. It's not in any of the
/usr/share/dict/ files. It's certainly not a word I've added and am able to remove from the
System Preferences -> Language & Region -> Keyboard Preferences... -> Text interface.
I did find it in
~/Library/Spelling/dynamic-text.dat, but removing it hasn't fixed the problem, and most of the words in that file are considered misspellings by the system anyway.
Another possibly relevant observation is that in Spelling and Grammar, the misspelled word is only found in the English dictionaries (U.S. English, Australian English, British English and Indian English). If I select any of the non-English dictionaries, the word doesn't show up in the suggestions.
Note: these are words that the system doesn't give an option to unlearn, and I'm specifically inquiring about how to eliminate them from the autocorrect/spellcheck system, not a workaround, such as adding an automatic text replacement for each one.
Edit: Another word that keeps getting miscorrected is "c'mon" to "c'mob". Spelling lists a bunch of other useless suggestions:
All of the suggested spellings are treated as correct.
"balderizle" is another misspelling contained in the spellcheck.