I just got a text from Joe M regarding a word someone had used in conversation with him. "SupposINGly? That's a new one on me!"
I wrote back to tell him that's why I started using the word "allegedly". I used to work with people, including a former manager of mine, who couldn't quite get that the correct word is actually "supposEDly". I was suprised at how many professionals, including people with various titles and initials after their names, used "supposably" in conversation.
Rather than embarrass anyone by correcting them, or letting them mistakenly believe that *I* was the one who didn't know what the correct word was, I started using an alternative vocabulary item to get my point across. Problem solved.