I teach A Level English Language and contstantly have rants with teachers about students' misuse if certain words (mostly related to course terminology).
Affect/effect being a prime example
Another is practise/practice and stationery/stationary.
I've never understood words really, it should all be phonetic, it makes no sense. why spend ages learning how to remember how to spell a word in a way that makes no sense ( maybe a historical one ).
it's a waste of time. plus i hate people who make u fell stupid just because they've mastered spelling. 9 times out of 10 that's about all they've mastered that and repeating stuff they've read.
language is a living thing and that means it should evolve and spelling differences are a part of that. people should be encouraged to make up there own words and spellings whilst sticking to a entirely phonetic frame work. and con-sine the English languages ridiculous spellings to the dustbin of history.