If a post is really spam or otherwise absolute garbage, you already have available to you a means of not only demeriting it, but asking for it to be deleted: That handy Report to moderator link you see in the lower right-hand corner of every post.
If a post that has been merited is removed, does the user that created the post lose the associated Merits or sMerits? I thought they got to keep both, but that's the only situation were I think the concept of demerit might work well. If the post no longer exists on the forum, it's hard to argue that it deserves any forum merit.
How about if the post merited is deleted? Will the merit count? Or erased too? Because somebody could just use merit for unreasonable purpose.
The merit is not undone if the post is deleted.
I like having to seek positive posts, it's a nice change of pace from always looking for negative activity... but a demerit option may be necessary in the future. I'm not sure a demerit option for everyone is necessary right now but it at least seems logical to drop merit for deleted posts by mods & users... there seem to be a lot of shitposters that have gotten into a habit of deleting their prior posts after a campaign has ended to hide their crap, and maybe this would help with that also, assuming they
somehow get merit for those posts.