There are scads of people who have experienced English primarily as a spoken language, and they can't spell for hell. Moreover, some of them cannot even really write. I have found that, almost invariably, they are very articulate speakers. It is as though their command of the language is tilted entirely towards the spoken word, with reading, writing, and spelling being a kind of afterthought. One way to spot this, is if when you give such a person something to read, either their lips move, or they start reading it out loud, word-for-word (or if they say "I don't have my glasses").
People who speak a highly vernacularized form of English, with the grammatical and syntactical mistakes these people often make, are especially prone to this. There is a large percentage of the American population that simply can't get their heads around "would have gone" as opposed to "would have went", "I saw" as opposed to "I seen", and so on --- once I was talking to a coworker who spoke in this "American joual
" fashion about "would have gone" and she said "hit just don't sound right".
And then there is the amusing habit of people in the Southern Highlands who think anything that ends in an "s" sound is plural, such as "license", "patience", "tux" (tuxedo), and so on --- "did you get your license? --- yes, I got them".
I even had someone, not too long ago, complain of not being able to take a pulse, "I can't find them".
They think such words are like "glasses" or "pants". And the word "an" does not exist south of Columbus, north of Atlanta, west of Roanoke, or east of Cincinnati--- "a apple", "a orange", "a egg" (which some pronounce quaintly as "aig"). Guess they'd really
be screwed if they went to New England and tried to order "coffee an' "
To be fair, I have a similar problem with Polish. With all their diacriticals and those evil clusters of consonants, if I am going to write something in my very basic Polish, often I have to stop and think about it --- I know what I want to say, I just can't summon up the spelling part.