I like the idea...

     I like the idea presented in this comic. Unfortunately, it won't work. As it currently stands, people already rate comments with which they don't agree "unconstructive," "unhelpful," "useless," or whichever term is used for the purpose. Alternately, if they like something, they will rate "woo, this is the ACE!!!!1111ONE!!1!1!" as "constructive." Spammers would, sadly, just mimic this behavior. Ultimately, no one who wasn't selling garbage would be able to get in.