No. They knew what it meant. Just didn’t realize it was the same word spelled as “misled.” Just like I didn’t realize “seg-way” aloud was the same word as spelled “segue.”
No segue is a real stumper. Misled is not.
But clearly it is for some folks. My roommate from my early 20s – a very educated man – confided in me that, as a child, he would pronounce “misled” in print as if it were the past tense of “to misle” not realizing it was the word he heard as “mis-led.” And others in this thread have, as well. It’s a very natural, IMHO, error.
I won’t deny that what you say may have happened. But I think he would be the rarer case.
Just a note on this. Googling suggests that the anecdote was in How Green Was My Valley. Any given English word may not have been in common usage in a small mainly Welsh-speaking village in the late 19th Century.

ETA: Actually, “segue” would work for me. Took me years before I realized “segue” and what is spoken as “seg-way” are the same word, and I heard the latter many times. I just read it as “SEEG”.
I had the same experience. In fact, I saw the word written many times, I didn’t even hear ‘segway’ spoken aloud very often.
I disagree, but such is conversation on the internet.
I’ve heard “segue” spoken often enough by then, like “let’s segue into” or something like that, and just either not noticed it in print, or glossed over it, not caring much for its exact meaning. It was only while reading a musical score for a musical, where a piece was titled “[Scene Name] Segue” in between scenes that it finally dawned on me that “segue” = “segway.” I was a senior in high school before I figured that out.

The brand of underwear and bras I wear is “Cacique”. Never once heard it pronounced and I’ve been wearing them 20+ years. In my head it’s “Ca-KEEK”. Am I anywhere close?
Googling suggests “ka-SEEK”. Incidentally, I never heard of the brand until just now.
Yeah, I figured it out a few posts above. So funny I’ve been wearing it forever and NEVER heard it pronounced.
It’s a plus-sized women’s underwear brand so unless you are such a woman or live with one, I guess you’re not going to ever come across it.
I must admit, I’ve always been a little puzzled by the “I never connected the word misled to the word I had heard as mis-led” thing, myself. If people knew the word from having heard it, how did they imagine it was spelled if not “misled”?
I dunno. Perhaps “Mis-led.” Doesn’t really matter. Perhaps they’d be able to figure out if they were asked that way, but upon coming across the letters “misled” for me, at least, it’s pretty easy to see how that would be parsed as “misle”+”d” and the connection to “mis”+”led” glossed over. I am almost positive there’s a word I’ve mis-segmented like that, though “segue” doesn’t work for that example. I"m reasonably sure I’ve done it for “cooperate” reading it as “coop” + “erate,” probably jumbling it up with a word like “recuperate” in my brain, but I know there’s another one.

To me, “general” does rhyme with “mineral.” Why would Gilbert be taken to task for that?
Because GEN doesn’t rhyme with MIN?
Sure it does.
When I was young, it took me a while to make the connections between the written and spoken versions of league and ally.

I must admit, I’ve always been a little puzzled by the “I never connected the word misled to the word I had heard as mis-led ” thing, myself. If people knew the word from having heard it, how did they imagine it was spelled if not “misled”?
I’m one of those who read “misled” as “misle-d” when young. I was probably a teen or pre-teen when I made the connection with the word I’d heard spoken. (And I thought this was just a peculiarity of my own, so I’ve been amused to hear others over the years saying they made the same mistake.) I think a good part of it is that, when hearing the spoken word, I wasn’t thinking about how that word was spelled — do people spell out everything they hear? There really isn’t time for that. The spoken language is independent of any way of writing it, as shown by the fact that general literacy is a relatively recent phenomenon.
I think that depends - I am 100% sure that I read the word “misled” before I ever heard it pronounced, because I read most words before I ever heard them pronounced.* It might seem strange for someone to think “misled” was pronounced “mizzled” when they have actually heard “misled” spoken - but it’s not so strange if the person has only read “misled”, never heard it and didn’t actually look it up in a dictionary. If someone is trying to figure out what a word means from context, deciding that the word means “deceived” isn’t going to help connect “mizzled” to “misled”
- I am not at all trying to brag, but I was reading about two years sooner than my peers. My father never finished high school and the grandparents who lived with us never started high school - and by the time I was in fourth or fifth grade, my reading vocabulary was larger than their spoken vocabulary. Not one of them would have ever used “misled”. They would have used “lied”.

ETA: Actually, “segue” would work for me. Took me years before I realized “segue” and what is spoken as “seg-way” are the same word, and I heard the latter many times. I just read it as “SEEG”.
Same here.

I’ve always been a little puzzled by the “I never connected the word misled to the word I had heard as mis-led ” thing, myself. If people knew the word from having heard it, how did they imagine it was spelled if not “misled”?
I suspect the way the brain acquires and stores these things means that the connection would not be automatic. It’s not as though hearing the “new” word misled results in a corresponding written entry being placed in an alphabetic list of written words in your head, only to discover that there’s already something there…
There was a question tonight on Jeopardy. Can’t remember hearing beat-i-FY pronounced. The contestant pronounced the word be-AT-i-fy. Suppose that’s right, although perhaps not, since he misspelled Austrailia.

I think you may have been mizzled about how often “misled” is used in daily conversation.
Ah larnt much of mah vocabalary, spellun and pronun-say-shun from reading Pogo and Li’l Abner when Ah wuz a chile.

At worst you will come off as educated in the classics.
Well as any fool kin plainly see, THAT dint happen.