Other than that "Mary-Sue" croc, another type of character that is heavly bashed are "self-inserts."
Though it's mostly bashed because people attend to lie about their characterstics, personalities, and flaws to make them sound better.
But not all self-inserts are like that.
If the person is being true to one's self (details, flaws, etc.), and if anybody knows that person, they'll see that the person's self-insert character has the flaws and quirks as they do.
As for making one's self-character inter-act, befriending, or even falling in love with a few characters (or vise-versa), a little role-playing doesn't hurt.
It's fun to do every now and then to except reality; as long as you don't go over board and think those characters are real and they are friend/boyfriend/girlfriend/sibling/other relation.
Even famous people put themselves in their shows, movies, stories, and much more, like these examples: en.wikipedia.org/wiki/Self-ins…
So the next time you see a self-insert character or create one, make sure you know the person before you go on saying their self-insert is a MS/GS.
And stay true to your persoanlity, no matter how embarrassing, weird, or distgusting your flaws and quirks are.