Yanbu at all.
It isn't even about knowing how to spell, it's about knowing what words to use.
I regularly want to bang my head against a wall when I work with one particular colleague.
Some delights from the past 7 days include
"I've ordered pink Moat for my wedding", to a colleague when she was serving a customer. Customer and colleague laughed, so she came bleating to me
"It is Moat isn't it. The champagne?" To which I corrected her "Moet is the name. Moet et Chandon"
"my brother just totally pampers to my eldest niece, she's so spoilt" instead of panders.
"I'm a great believer in Cava" again to a customer who had been talking about some misfortune or other. I actually had to leave the shop floor to laugh.
"If she doesn't stop nagging, I'll smothercate her" that was yesterday, about our manager.
My tolerance is rapidly being worn away working with her. Her spelling is wild and her handwriting is expansive, shall we say?
And yes, she does say Could of, Would of, etc.