The cases I refer to were Starship Troopers, Stranger in a Strange Land, and Rocket Ship Galileo, which he wrote in the late 1950s and in 1947. (Your Heinlein clock needs recalibrating – his “classic” stuff was mostly from the 1940s and 50s). I’m not sure how common the un-accompanied “so?” was as an expression back then, because I wasn’t around.
That would actually be a useful response. Jesus could’ve fixed him right up. I wonder if his fingers would have gotten regrown if that had happened?
Speaking of vocabulary, I picked up South by Shackleton with an initial feeling of dread that it would be difficult but found it one of the fastest, most enjoyable reads ever. It took about no time at all to ken the numerous terms he used for ice, and the style was clean yet rich. Then, halfway across Antarctica lay “sastrugi” and “finneskoe”, two words I was wholly unequipped for. It was a strange anomaly in an otherwise easy book.
In my head and thanks to Samantha Bee, this word may now be applied only to Ivanka Trump.
In a subsequent book, Sinclair Lewis described something as “babbitry.” Yes, the word was in common parlance already when he used it, but it still just looked weird. I don’t know why.
Yes, I know it’s not what the OP asked for, exactly, but I can’t come up with anything else, because it’s on my mind now.
Nathan Lowell writes wonderfully down-to-earth tales of life in space, but at some point or another, nearly all of his characters ‘scamper’ somewhere.
Of all the cool things one can do in free-fall, I’m going to suggest that “scamper” is not one of them.
Or do his ships have artificial gravity? Or are the stories set on other planets with inherent gravity wells?
Artificial gravity. There are often injuries when it goes out, then comes back on with people not in contact with the floor. I do recommend his work, especially the Ishmael Wang stories.
I’d argue that, unless you’ve got some sort of a propulsion system on you, “scampering” is going to be your primary method of moving in a low gravity environment.
There’s a world of difference between low-gravity and free-fall, though. In zero-g, you can clamber, but I don’t think you can scamper.
90% of the time, if you replace the question mark with a comma, and attach “so” to the following sentence, it makes a lot more sense. It’s a fairly common verbal tic where I live.
Hmm, I always thought of scampering as basically quadrupedal, but I see that’s not actually part of the definition. I usually think of “scampering” as something small woodland creatures do, and pulling yourself along a surface with your hands and feet in zero-g feels analogous to that.
I don’t think Heinlein’s using it that way. It’s not like “So, if we go here, this will happen…” It’s more an answer or even confrontation:.
“I think we should do X”
“So? Well, that might not be the best answer…”
“I think we should do X”
“So! You’re an idiot!”
“So, you’re an idiot?”
Where I live, it’s usually more emphatic than a comma, but usually not emphatic enough for an exclamation point. More sarcasm than anger.
Craig Alanson is my current go-to writer for guilty pleasure space opera. Boy, does he love the word, “shmaybe”! 14 books into his “Expeditionary Force” series and it’s not just the first person narrator and his alien AI that use it; now other characters are using the expression, too.
I went through a patch of reading John Irving novels about twenty years ago, and while he tells a ripping yarn, his utterly gratuitous use of italics for emphasis gets a bit wearing.
Or…while he tells a ripping yarn, his utterly gratuitous use of italics for emphasis gets a bit wearing. 
I came in here to say the Heinlein “so?” thing.
FWIW, I lend my voice to the view, which seems apparent to me from context, that he used it not as short for a defiant “so what?” but as short for “is that so?” Like the way some people would say “really?”
Not a repeated or necessarily misused words, but I got pretty tired of Cormac McCarthy’s flogging readers with his vocabulary of arcane words, using the 5th archaic definition, etc. No, you shouldn’t write for 4th graders. But nor should a relatively well-educated/read person need a dictionary quite THAT often.
Have we mentioned Stephen King’s overuse of brand names to, I guess, make it all more authentic?
“As he drew on his Marlboro, he snapped his Zippo closed and tucked it into the front pocket of his 501s.”
This is why I could not finish “11/22/63” and why I have avoided King ever since.
mmm