We don't have a checklist to use as guide, to help us determine the fake from the original. So I listed what I've gathered from all those reports I've made. I made a post like this before but I couldn't find it. Anyway, I added new ones in this version. 

1. Inconsistencies: The original writer would know the names of his characters. So if the baby Kyuhyun suddenly becomes baby James in the next chapter, type a portion of the foreword or chapter and paste it in Google's search bar. Same goes with locations. The story is set in Seoul, so if you suddenly find yourself in Madrid or in Paris when it was never mentioned that your characters teleported there, be suspicious. 

2. Unique terms: A friend remembered a flavor of a milkshake (or was it a smoothie) because it was not a common flavor and so when he (or she) spotted it another fic, he tried to recall where he read it and true enough, plagiarizer made a Girl's Day oneshot collection version from two SNSD oneshot collections. I discovered another author's deceit when she used a term so different, so unique in my ears that I had to do a quick google check. Sigh. User plagiarized two published novels. Her fic has 48 chapters already when I reported it. 

3. Odd symbols: When users copy content from other sites, being the lazy bums that they are, they forget to edit. So if you see those boxes with an x, a skull symbol, or an interrobang instead of a period or comma, chances are that the fics are lifted somewhere else - usually a forum like soompi. 

4. Kawaii greetings and overflowing kawainess: Mangas usually start with character introductions - name, age and school info - so it is pretty easy for me to catch someone who lifted the story from a manga. A common tell is if the main character talks like she drank truck-loads of orange juice. 

If a fic merely changed the names of the characters, that's plagiarism and not a kpop adaptation. You may take the premise and credit the mangaka but you write your own scenes. The same applies with movie and novel adaptations. Just because author gave proper credit doesn't mean author is off the hook. Credit doesn't mean anything. Ask permission and then credit. Fanfiction is transformative work. If we still see more of the original in your work, that's not transformative.

5. Patterns: Stories, even cliches, have differences. So it is pretty obvious when two stories are so similar in so many ways - same conflict, same response to conflict or same resolution, or even the minute details like hobby or that place where OC and oppa would go when they are sad, etc.

If you plagiarized another story and you are reading this, even if you edit your story based on Keeper's list thinking that you could escape notice, you are wrong. Because the sixth and the ultimate tell is not something you could easily bypass. Mwuahahahahahaha!

6. Gut feeling. Contrary to popular belief, this Keeper doesn't police or monitor the site. I don't check all the stories that appear in the homepage. Plagiarized fics have a way of finding me. Really. Like you, I am only searching for a fic to subscribe to. I read the titles and what little can be seen of the description. There are no red signals or glowing texts telling me that the fic is a copy or that the user is a plagiarizer. I just feel it. And me being a science student should be looking for a more logical explanation, but you know, God works in mysterious ways.  A friend can attest to this gut feeling. She  felt it too. (I found the Soompi plagiarizer because that user has good taste in fanfiction. The stories he/she reposted are well-written, so well-written, I was able to differentiate the voices of the writers. There were four, I think. And then after a few months, I went back to that user's profile and he reposted more. But that won't happen now.)  

Other tips:

1. Before sending the report, do check the user's other stories. 

2. Install the Awesome Screenshot app from Google Store and take captures of the whole page or part of the page. It is better to have evidence. So that even when user decides to hide the fic, you have something to show the moderators. Privacy options don't work on mods.

3. Here in AFF, anyone can send a report via the report link button. (No need to inform author.) Hit that link and then paste the link of the original fic. If you want to inform original author, let author send the report. No multiple report submissions, okay? Tell the author that it's okay to rant about it or pour out his/her feels in a blog but don't drop names or links. If anyone of his/her readers/fans bash or bullies the plagiarizer, author will be held responsible. 

4. If it is not a word-for-word copy, do a pattern analysis; list the similar elements. Use the Awesome screenshot app to take shots of certain parts of the fic for easier comparison with the original. Let's not forget the existence of common storylines or the cliche plots and stereotypes. Before you go accusing someone of plagiarism, ask for a second opinion.

EXTRA: Read Intellectual Plagiarism. The writer of this article defined it as "leeching plot and character ideas from other writers". Here is the example she gave: 

"Some time ago, my friend Alanna wrote a FF7 fic in which she gave Hojo a first name, which was Simon. Now, nowhere in FF7 does it actually say that Hojo's first name is Simon; in fact, he is given no first name to speak of. Since he wasn't given one, Alanna made one up for him. This is one of the things that fanfiction is for: improvisation and filling in gaps. When you want to write about a character with blank spots in their personal history, you invent your own. However, since she initially wrote that fanfic, I've seen more than a few people referring to "Simon Hojo" in their fanfics-- despite the fact that they weren't even writing within her FF7 continuity. Moreover, not only were they using the name, but her entire concept of the character-- his history, his personality, ad nauseum."

Intrigued? Read on.

Thank you for the comments  in my last post :3