I've often seen suspicious answers on SE. They're too detailed, well formatted. I put some of the body text of the answer in Google and I quickly spot the original source.
E.g., I flagged this one as plagiarism:
The answer was lifted verbatim from Dell Secureworks. Not a single word of the author's own text appears in the response, and there's no attribution.
Do we want to fix the answer or just flag and delete? Plagiarism of this kind is frustrating to me. This particular level of plagiarism is so severe that it's copyright infringement. It should not be tolerated.