I came across this article in the beginning of the year. Read it. Agree with it. A bit guilty of it. Now every time I read a book, before I stamp the main character a Mary Sue, I ask myself: if the main character was a dude, would I still stamp him a Gary Stu?
Now, it's near the end of the year, and I believe I have improved. I have identified more Gary Stu's than Mary Sue's. Overcorrection? Maybe. But I am prepared to justify why, and my reviews are better (and longer) for it.