Everyone has different tastes in shirt designs. I don't understand how you can judge different shirts when everyone has different tastes. Here's what I think this site should do:

first, have different categories with different criteria for the designs that go on the shirts, i.e. a hip-hop themed category, a nature themed category, an urban category and etc. Then, each week choose the shirts that should be printed from the top voted shirts in each category. My point is, this site is much too broad and diverse to have just a bunch of shirts thrown in a big pool that people choose from; narrowing it down to category and theme would be a good idea.