Heh, you think it's rough here, try out some of my sub-Reddits.
Upvote/Downvote etiquette is that you upvote anything that's well-written or stated, but I don't really follow that. Typically I'll only upvote comments I agree with, regardless of how well-written a post I may disagree with is. I only downvote comments that are legitimately breaking the rules, flaming or trolling, etc.
Personally, I really dislike the system, since it's so easily abused. I usually favor giving that power to admins or moderators rather than to a mob of downvoters.
NNID: Zephyr25 / PSN: Zephyr--25 / Switch: SW-4450-3680-7334