That sort of defeats the purpose of the reputation system, no? If there is no way for your reputation to go down then there is a lot less reason not to spam.
The second idea is interesting, but it doesn't really work with the downvote.. The point of the downvote is because a post doesn't contriubte/ is spam, so if there is anything worth commenting, then you shouldn't be downvoting anyways.
That sort of defeats the purpose of the reputation system, no? If there is no way for your reputation to go down then there is a lot less reason not to spam.
The second idea is interesting, but it doesn't really work with the downvote.. The point of the downvote is because a post doesn't contriubte/ is spam, so if there is anything worth commenting, then you shouldn't be downvoting anyways.