If you were to do the same to someone else's book character, what would your criteria for Mary Sues be?

Frankly, I was not even aware of the term until very recently, not long before I came across the Echo comment. And it was my understanding that it was a term intended for certain sort of fan-fic character. That said, I think this is all a bit of a non-issue. And I doubt I ever would use such a silly term to describe someone else's character.