I just made a post:

It would be nice if the community can downvote a post like this in case it contains wrong/bad information that would cause someone following that advice to end up damaging their board, or something along those lines.
For example I am new to working on beige Macs and dound this battery holder a great option. But if those more experienced at this feel this is a horrible suggestion for whatever reason, their ability to downvote it would let the rest of the community know it's potentially bad info. Rather than just delete it, downvotes and a discussion in that thread could be a big help.

I say downvotes but any kind of flag to indicate *potentially bad info* would work. With enough downvotes the admins/mods could review the post and see if it needs to be edited or have a warning slapped on it at the top of the post (if the author does not want to edit it).

Maybe a Mac with question marks as eyes?

It looks like Xenforo theoretically supports this - but downvote buttons can be abused. I think once we're better established, mods should look at the cases individually and suggest to the OP of the thread/post that they might want to change what they posted - users have the ability to edit all their posts, or remove them entirely.

For now, i recommend using the 'report' button on a post, and we'll look into the postings :)

Being on reddit quite a lot and coming from that point of view, I honestly never found downvotes that effective. All they did was allow a subset of people who disagreed with you (even if your information was good) to drown you out. As Kai says, I think in cases where the downvote would be applicable, you should just report since I think this forum would be WAY more strict on moderation, anyway, so less chance of that happening, IMO. But it's still the early days so who knows!