I feel like this particular case--so many people use it interchangeably nowadays that it's becoming synonymous. Like I never hear people use jealousy correctly in every day speech--it's nearly always as a synonym to envy. Not to say it's correct, but I think the English language changes so much and there's so many places where it's colloquial that it becomes more of like a formal thing to remember to use some of those words the right way (I say as I fix where I double spaced at the beginning of a sentence because apparently we don't do that anymore either).
Affect and effect though--those are science terms, I feel like that one isn't going to become synonymous ever. Definitely a pet peeve of mine when those are mixed up (and a mistake I make myself often enough)