The most effective way to avoid spam is to read before you post: This could be previous discussions or external articles related to the discussion. It's best to read more than you post.
Half the time it doesn't even need to be external articles or other discussions; if the user in question just read the other replies in the thread they were posting in, they would realize the content of their post had already been said before. Most spammers read the OP's post only (or sometime only the thread title), ignore all other discussion that follows, and chime in with their opinion which has either been said 10+ times before or already proven wrong.
There was a recent thread which I answered the OP's question factually in the second or third reply. The OP, myself, and a few others continued the discussion from here, but I had to report many posts from users showing up and (incorrectly) answering OP's original question, despite the conversation having long moved on. If these users had just read the replies, they would have no reason to post.
The problem is these users have no desire to read. They don't get paid for reading. They get paid for spamming. The quote you gave from hilarious would be a great system, but unfortunately it is barely enforced.