Besides the problem of animals getting hurt, or sick, or out, or bitting someone (and causing legal issues)...
My question is Who Does That? Seriously? Who does crap like that? How about I go down the street and go into my neighbors house and rummage through the frigidair and check out her shoes....Its ok, because I met her kid once getting the mail. Doesn't fly does it?! I must come from a very rural area because if some one did that to me I would go ape $&!% on them. Buy a good lock and give that roommate a solid piece of your mind. He's responsible for bringing her in- therefore responsible for her actions.