Sometimes it is not that easy to identify that a word was misspelled. And, if you don't know the word was misspelled, it can be very embarrassing when someone else points out the spelling error...particularly if you make the mistake in a very public way - like while writing on the blackboard!
Check out the other slides in this slideshow for more potentially embarrassing situations that a bad speller can get in to.
But, using a spell check program can be embarrassing. When a really bad speller types in the word, the spell check program often can't identify what the speller is trying to say and does not have a suggestion for a new spelling.
Sometimes a really bad speller will have made so many errors, or such egregious errors, that the reader has a problem reading what was written.
That's the point that you realize that the tattoo on your arm is misspelled.