Meet the T-Shirt Trolls

If you've spent any time at all in the gift shop and cafe reception area, you've probably noticed that the staff aren't exactly human.  The gift shop and cafe reception area is staffed entirely by the T-Shirt Trolls, a sub-race of the troll species that is uniquely gifted in the creation of T-shirts*.  The trolls were hired by the Tower after their former place of employment, 'The Bargain Brigand, was shut down.  It turned out they were literally robbing their customers**.* The reasons for this are not entirely known.  The trolls themselves will mournfully explain that it's a curse of some sort, but the story is incredibly boring and no one's stayed awake long enough to hear the whole thing.
**Happyshine authorities were quoted as saying "We probably should have suspected something amiss by the name of the business, or the folks turning up at our office saying "Please help! I was literally robbed at Bargain Brigand!."  Our bad."