I've also been on the site reading fics for, i don't know, seven years? I have only once come across with someone copying shit from an author who's no longer active. The story is still up, and I remember when it came out people were shitting their pants. Turned out that too many remembered the story, or had gone back with a 5 point filter in search for good ones.
BUT eventually what happened was that the author claimed to be the same dudette who posted it years ago under the old username. There's really no way to know whether it was true or not, but I hope it was.
I agree with Lolhai that there's a fine line between stealing a plot and doing your own thing that you just don't realize has been done 10759 times before, but plain plagiarism is just unrespectful and rude.
I mean, if you can't write or come up with a storyline to save your life (or atleast give it a fair try), then get the fuck over the fact that it apparently isn't one of your many talents and move on. buy a marionette or something.
Who's stupid enough to feel great about themselves when they get praise for work they never did, anyway? It's like the lamest sort of self-deceit i have heard of :D
Author's response
Well in all honesty if they were reposting the story they would say so at the start. I have seen that, but it was an updated version of the story (a story I loved btw). But i think some people believe they can get away with copy and paste because the stories had been posted years ago. But there are people like us who have been reading on this website for many years and notice these copy and paste things instantly.
S xx