I think it's just random. There was one time they swapped your regular clothes for some revealing outfits [That's definitely a smirk on her face, as she thinks of the unfortunate people who had gotten caught in that particular trick.] and that was after the faceless nurses.

[Korra shrugs.] You just have to be careful when you sign in. [A pause as she looks him over.] If you haven't heard all this before, it means you're new, right?