I hate people in the Art Portal that don't really give a shit about your piece, but would rather just submit a review of anything radical like 0 or 5. Give it some real thought, idiot, this is the ART PORTAL. Give art some respect, it's as difficult as Audio or Flash, believe it or not.
Rabid-Animals
People tend to remove themselves from the process of creating an artistic effort, be it Flash, audio, or visual. They feel entitled to entertainment, and when they see something that they personally don't find to their liking, they take issue, and vote poorly.
I haven't experienced this in the Art Portal because I'm not scouted yet, but I'm in all of the other Portals. As time goes on, you learn to not worry about the whines of people who don't try art. It's just something that you have to deal with as an artist.
Don't worry though, there are plenty of people on the site that vote fairly and leave helpful reviews.