I don't know if this has been suggested before (I searched and found nothing, please don't flame me), but what about a -rep button in addition to the +rep one? It can be very useful when someone:
- Post useless or non working stuffs just to try to make some rep.
- Post things like the mail "Greetings, it has come to our attention that you are trying to sell/trade your account." (common sense, repost and very old).
- Make a copy-paste.
- Ask for rep at the end of his post.
- Attempt to trade in wrong sections (optional).
Maybe I forgot something, but you get the idea.
Obviously the button should NOT be available to all of us. Just imagine a leecher that starts to give -rep to good contributors. I suggest to make the button available only to trusted members such as contributors or higher (not even donators if they have just a few rep and posts).
What do you think?