General rules I have noticed even after points stopped being show are (mostly regardless of the actual facts):
Take Apple's side(except if it's against Google) = upvotes
Take Google's side(except if it's against Apple) = upvotes
Take an anti-MS stance = upvotes
Take a non anti-MS stance: downvotes or no upvotes
I bet you can literally farm karma by following the above rules, based on seeing some posters' karma.