I disagree with that. Sure, if it is a carbon copy of another, better story, than there is no sense in reading it. However, there are many stories that are similar to each other, using the same cliches, but a few of them are gems that are worth reading many times.

Examples of people trying to be too original would be Miranda Flairgold's A Second Chance at Life, which mutated from a good post-HBP independent!Harry story into a fantasy novel featuring some guy named Rahkesh going to some school in Canada with Vampires, super-powerful elves, and a random South American tribe.

With all of the fics out there, it is almost impossible to come up with an original idea, but if you use cliche after cliche after cliche, then the story isn't worth reading.

 

I dont touch anything that has some "mysterious" person in the summary or some phrases like "Harry and the gang". In those cases I dont even finish to read the summary.
And its a sure sign of a poor story if the summary is a list of terms like "quidditch, pranks and lots of fun".
I generally dont read fics that have romance as one of the categories. That usually means H "has the strength to fight because of her" or she always has to be the one to kick him in the butt if he's is lazy or whiny and in those cases I really dont care which girl it is.

 

...Thought I might add a few.

'Mom'. Don't hate me, Americans, but it just pisses me off - if I see that spelling, I can't stand to read further.

Anywhere that Harry is slated as a Sex God - or made out to be ridiculously, devastatingly handsome (in a non comical way).

And, strangely, hair cuts. I'd rather they were just not mentioned - especially longer hair on Harry (rare fics like 'The Happy Red Prince' being an exception to that).

I think the first paragraphs are incredibly important too - couldn't stress that enough. And it's amazing how many people screw up the grammar in dialogue! Agh. If people can't be fagged hitting the damn comma key ...