See this question: http://askubuntu.com/questions/163613/offline-installation/https://askubuntu.com/questions/163613/offline-installation/: top answer, third comment. I told the commenter that it's better to correct the answer himself than to threaten others to do so.
But I'm still not entirely certain if my reaction was correct. It's good if answers or questions get better this way, but that having said, it seems a bit rude to me to force that by threatening with downvotes.
Is it acceptable to threaten with downvotes?