Do Erratic Sims generally go around sans clothes??

Yep. Gotta love em. They're predictably unpredictable! You can almost guarantee they'll do the things that make you shake your head and smile. Always been like that too! I remember my Sims 2 erratic sim would dance in the bathtub and play submarine in the empty tub like the kiddos did, then she'd dress in her formal wear and go weed the garden.