Do intelligent people switch 'effect' and 'affect' or say 'irregardless'?

No.13353992 ViewReplyOriginalReport
I have always thought not, but then I saw the brightest mind of our time say 'irregardless'.
Also I have very often seen people on /sci/ present solid arguments but use 'affect' when they mean 'effect' or vice-versa.
Am I a snob, am I pedantic, do I take my education for granted, or are there actually different kinds of intelligence?