I get randon 'b',v' and 'n' on the ipad when I'm in a rush, hit those instead of the space bar at the bottom. Interestingly rarely 'm', wonder why? Oh dear, I know what happens when I rush but I still do it. Hopeless case.
Spelling/autocorrect errors (on a forum) on the whole, don't bother me. I do get slightly irritated by a post immediately following it, correcting it. Unless it changes the meaning of the sentence, then it's usually obvious what the poster meant.