Oh Steven... your last line is so much to the point I would have liked to make. Why even bring up about fair use? (I know you didn't). This question has been asked and answered in this forum at least a dozen times.
Although most western nations are in accord with the Berne convention, it is my belief that, unfortunately, those who ask "how much can I use" have no intention of following the law of any country. They may just as well ask, "How much can I steal before I get into trouble."
I've yet to see a post that specifically asks about "commentary, criticism, news reporting, and scholarly reports", just as I see few posts about how to give attribution to the author and fewer about how to contact the author of a work and ask for permission to use it or a passage from it.
As D'Crux said, it's all about "writing avoidance", IMO, from a bunch of lazy, unskilled hacks that want to fill up the Internet with rehashed, copy/paste, day-old, already-been-chewed writing.
So why even HINT that they can get away with it? Just say "NO" to plagiarists and to those who aren't -- be specific in your posts if you don't want to be branded a thief.
Last night I was looking for a recipe for chili dog sauce and I found six of them at very popular recipe sites. Funny, though -- every single one was exactly (to the letter) the same as the next.
To the op: Why don't you go look at the terms and conditions of use at the original site? They are often different depending on who owns or manages the domain. How on Earth could anyone here know all of them?