A "Duster" too far

If you read fic of any kind... you know how sometimes, you read something and think, "Oops. We/They would never say that"?

And how, sometimes, you think, "oh well, it's just a simple mistake." and don't let it spoil your enjoyment of the story?

But then you see the same mistake made by someone else. And this time, it jars a bit. But you again think "oh, well," and keep reading.

Then you see it in another fic.

And it jars even more.

And another.

And another... and another... and another... and...

( Today, I finally snapped. )