I'd be interested in how a few of the companies (not just teefury) get away with it, or if its just plain luck so far. Some of the properties are worthless besides fan art, but others like star wars, motu, smurfs, etc... there is still a lot of licensing going on. Personally, I think copyright has strayed way beyond its bounds in this country and has started to take on an EU appearance, which isn't a good thing for those who value freedom of information and innovation.
mighty fine has some really nice Adventure Time shirts too(and theirs are officially licensed). Then again they are $25. http://www.welovefine.com/
I agree, I bought a Jawsome shirt and hardly wear it because it just fits weird and doesn't feel right. They have great designs which just make it worse. No problem with the screen though.