I was on a (pristine; just like new) Air France 747-400 from CDG-LAX, and the emergency exit at the left wing was inoperative on departure.
The overhead signs had been taped over, and crude signs directed passengers to the opposite wing exit.
The safety card did not indicate that the exit in question was inoperative; and neither did the announcements at take off.
A crewmember told me, "It's no problem."
Apparently, a 747-400 departing from France can depart with at least one INOP emergency exit.
Is there a standard on this?
(an unrelated note: the AF flight crew made a REALLY HARD landing in calm winds at LAX - - so much so that a substantial ceiling assembly broke loose in the main cabin ... it was a hard enough landing to make one think about emergency exits)