This may come as a surprise to some, but a lot of writers can't spell worth beens [sic].
Flannery O'Connor, one of the greatest American writers of the 20th century, described herself as "an innocent speller." She barely passed spelling in school. Certainly there's no malice intended, it's just not a skill some writers possess.
One of my favorite writers--and colleagues--is a poor speller. I don't mind a bit, though. She's so gifted at her craft, that I love everything she writes. And her bad spelling affords me job security.
But I do have to pay special attention to her spelling. This came in recently:
"The principle researcher for the study..."
Make that principal, as in the lead researcher.
Usage here can be confusing. Merriam-Webster's Collegiate Dictionary has the following unhelpful note:
Although nearly every handbook and many dictionaries warn against confusing principle and principal, many people still do. Principle is only a noun; principal is both adjective and noun. If you are unsure which noun you want, read the definitions in this dictionary.
Principal often means the head of a school, so some think of the Principal as your "pal." (Where did they go to school?) Principals lead schools, so it makes sense they would also lead research or study groups or be the main item on a list. Principal also refers to the amount of a loan that draws interest.
Principles are generally rules, doctrines, or precepts, as in the principles of mathematics. One also hears of the fundamental principles of human rights, for instance.
Principal misspellers haven't mastered the principles of spelling, that's all.