'Critics have accused this story of giving birth to the era of "grim and gritty" comic books'
-- The Dark Knight Returns entry at Wikipedia.
'Tim Burton later adapted the comic's bleak sensibility for his first "Batman" movie, and since then, countless comics creators have aped the "grim and gritty" milieu.'
-- San Francisco Chronicle
'Overall, a very cool image that suggests Batman Begins will return the franchise to its grim and gritty pre-Schumacher days.
'If the original Dark Knight seems almost normal today, it’s because... it set the tone for the wave of “grim and gritty” superhero comics that’s still going on.'
-- Portland Phoenix
'Comic book writers wrestle with his dark, grim and gritty traits while trying to make him a mainstream hero to whom readers can relate.'
So, to recap the conventional wisdom: Batman sucked until 1986, when people began to describe him with the grown-up sounding "grim and gritty."
Well, I found the earliest known citation of the term as it relates to Batman, and it will shock you. I am not kidding. It's true, I swear. And you'd better be sitting down:
NARRATOR: When last we saw our beleagured battlers, they were slowly sinking in a bitter batter of Riddler quicksand! A grim and gritty end awaits them unless something awfully good happens awfully fast!
-- Batman, A Riddling Controversy, first broadcast February 9, 1967
So, to all of you people who take the Dark Knight oh-so seriously: your very mantra comes from the ADAM WEST TV SHOW! When he was trapped in a GIANT CAKE! HAHAHAHAHA!
Sorry. It's just... HAAAAHAHA! Oh, God!
[Hard evidence here.]