For me it would have to be any character in a Brandon Sanderson book who is witty. Shallan or Wit in Stormlight are a great example of this. Both default in either reprimanding someone for using a metaphor, a simile, or just a phrase, and pointing out how indeed, it’s not like that in reality. Another would be dumbing everyone around them down to be impressed by this every time these characters talk like this. It never really made them come off as appropriately witful, just the type that actually would say “AKSHUALLY”.
Moby Dick goes into gratuitous detail on whale hunting, and Melville worked as a sailor and whaler for years.
Grevious mistake. Title is supposed to say “doesn’t know”. Oh well, repost time
GRRM clearly knows what he is talking about when he describes food
Michael Crichton’s medical training really comes across in his books.