The question is whether those statistics are indicators of success or do they hold true for ALL t-shirts of threadless.

57% of the success may have had humor because 57% of all tshirts submitted had humor.

given a metric like `50% use 2 colors or less`, this by itself doesn't mean much to me because in the general population 70% may use 2 colors or less. Or 50%. or 10%. I don't know the general trend, so I don't know whether using 2 colors or less is a good idea or a bad one.

I'm not knocking your study, personally I found it really interesting.