Yea, I'm trying to make sense of the dynamic over here too. Seems everybody generally has different taste than I do, which I'm taking into account (e.g. the winner is too cutesy for me, but props to pspens for a winning design that fits the theme and is very well done).
There does seem to be a noticeable hivemind. It's way worse than the one over at deals.woot because we're talking about shirts actually going to market here. I guess I'll never be able to tell how many of these votes are popularity contest, but I suspect quite a few are artist-votes rather than art-votes.