Careless quoting is a writing crime. Fiction or nonfiction, a writer must be scrupulous in quoting words precisely and crediting their source. Most publishing contracts hold the author liable for misrepresentations and plagiarism, but even without that legal pressure, a writer, of all people, should naturally respect the intellectual property of others.
In the old days, authors wrote out their source citations from scratch, and editors checked them to make sure they were correctly formatted. Now there are tools that will do this for you, from online “Cite” buttons to full-featured citation management apps.
Many of us would benefit from frank conversations with other scholars about improper borrowing, otherwise known as plagiarism, but the topic is so hot that most professors avoid discussing it, except in warnings to their undergraduates.