news.yc Bug: Upvote more than once

Looks to me like trying to vote multiple times this way will keep on updating the web page you see, but the server only records one vote.

news.yc Bug: Users can get free karma points by posting a submission claiming that submissions can be voted on more than once. [1] [2]

Personally I'm wondering why I can't downvote comments. Not enough karma yet?

Correct, you need around 20 I believe.

.... or just keep clicking the invisible arrow. Your mouse even turns to the usual pointer cursor.

And as cperciva said, they don't register on the server.

do some people have enough karma to downvote submissions?