In my case, I don't think I've ever had a character wear the actual prison clothes outside the Tutorial Dungeon. By the time they've made it out the sewers, they're wearing some armor, or in the case of a couple mages I've had, they'll be wearing the Mythic Dawn cloak & hood. The prison clothes ALWAYS get discarded.
On the other hand, I've had at least 2 characters that I can think of who don't mind wearing the Sack Cloth clothes & shoes when it's safe to do so. Dyan phor a'Cauz is one of them (she has a desire to appear "humbled" when she's in town) and my Slave/Theif character (Wanda Bone, who is now deceased) is another. Wanda actually liked going to jail! :clap: It meant she could get some peace & quiet.