Even people who consider themselves to be good at spelling have a group of words about which they are unsure, and have to check, so no-one is perfect.
The standard of spelling in schools is, in my experience, very poor; but that also goes for geography, history, science etc. Why ? Because the curriculum is too broad, and cluttered with things like ' Citizenship' and PHSE. But the main reason for poor spelling ,in my opinion , is that most children no longer read for pleasure, as they did when I was a child. We learned to recognise words and. of course, recognise how they are spelt. A good reader is a good speller.