[tneu89n43nth]

I think downvoting is one of the things they got absolutely right over places like HN and reddit. When you downvote someone, you lose rep. And you can't downvote until you have a certain amount of rep, if I recall. (Or maybe once you hit 0 you can't downvote?) But it really makes you stop and think, and it makes serial downvoting much less of a problem.

[shagie]

Down votes on questions are free. Down votes on answers cost 1 rep.

You need 125 rep to be able to cast a down vote (votes for people and anonymous users with less than 125 are recorded in an anonymous votes table ( for example, http://data.stackexchange.com/stackoverflow/query/209365/ano... ).

Hacker News has down votes too... and you can't down vote until you get a certain amount of karma.

The rep lost from down votes are an investment in site quality that you get back if the post is deleted.

[allannienhuis]

I've never thought twice about the cost of downvoting a bad question or answer. I only downvote things I think are more harmful than helpful (incorrect or really-bad-idea or misunderstood-the-question type of answers).

Maybe that's not how most people do it?