Should downvotes be given for spam?
Spam ain't good so in my opinion I think if a content contains spam then the downvote is worth it.
Who should give the downvotes and should we be responsible before the community for any downvote given?
Everyone has his or her powers to either upvote or downvote a post. When it comes to downvoting a post, I think a particular reason should be given by the user who downvoted the post in the comment section so everyone could know the reason that triggered the post to be downvoted.