When the author posts the story to her own website or archive account or LJ, and indicates that she's presenting the story as something she's created, that's the point at which criticism is appropriate

I agree, entirely. Until the fic is presented, name attatched, to a public space that fic wasn't written for the public TO criticise.

A fic that's published on the 'web it's published, it's out there for public consumption, it's the writer going "see what I did" and, IMO, requesting feedback.

When it's a fic exchange gift? No. It's something that was written for a single person. That's the difference for me. The audience.

Until it goes up in a comm with a name attatched, it's not there for me. I'm just a happy voyeur who needs to keep their mouth shut.