I remember there was a word I always wrote wrong until someone corerected me, don't remember which though. I saw it written like this all the time so it had to be right, turns out I was wrong in that assumption.
I do have problems to understand native english speakers sometimes, even in text. I don't know all the slang terms and if I look it up on urban dictionary it will with a 90% chance be some kind of weird sex practice.
My common mistakes are typos like: becasue, jsut or can'T.
That's a bad premise to go by because it means as long as there is a bigger issue you are not going to care about anything.