How Flawed is Too Flawed?

(This post is partially inspired by this post at i09 “10 Authors Who Wrote Gritty, Realistic Fantasy Before George RR Martin”)

The dark, dangerous, and flawed characters of Martin’s “A Song of Ice and Fire” series haven’t always been the yardstick by which characters have been measured. Fantasy and Sci-Fi characters have not always had such a “realistic” feel to them. In fact, some of the first and most recognizable SFF characters started out barely flawed if at all (see: Superman).

But as society has developed, so too has our understanding of the Human condition and our desire to have our fictional characters mirror, in some way, our own reality.

On the one side of the matter is the “Flawed Hero”. This character is defined by their positive traits, but it is their character flaws that make them interesting and give them depth. The good-hearted scientist who has an anger problem and turns into a hulking green monster, the “Chosen-One” who sets aside his destiny until the very last minute in favor of exploration and freedom, or the hot-shot pilot who smokes cigars and has a temper. All are modern characters who have flaws that define them.

And it’s not always bad traits that are character flaws. Take Ned Stark from ASOIAF. In a world built on deception and back-stabbing, his loyalty and honor are his character flaws.

But what happens when character flaws go too far?

For those fans of The Walking Dead, Shane’s overly aggressive approach to situations and willingness to sacrifice anyone makes him a character whose flaws carry him into unlikable territory. Or Gaius Baltar from Battlestar Galactica; his drive for self-preservation and willingness to do anything necessary to save his own skin leave him in a place where viewers have a hard time empathizing with him.

On the other side of the coin is the Anti-Hero, who’s reality comes from their good traits rather than their bad. The Punisher being the poster child for the Anti-Hero, followed very closely by Deadpool.

So where is the line between “Flawed Enough to Be Realistic” and “Too Flawed To Like”? What are your thoughts on the current trend toward seriously flawed characters and realism?