THEORY 1: There was a pin-up series not long ago with the school girl costume, so it would seem reasonable to assume people would be more likely after something else. Hence, why Becca got pigtails to bring something new and offset it, but Notty still didn't expect that option to win (or did, but it wasn't planned).
THEORY 2: Pin-up series was never finished, only pictures an impartial observer could describe as "teasing" were posted. Clearly, it was a plan all along to deny the good patrons back then, so that they would jump after the option in the poll. Pigtails were added to reinforce the scheme.
As a firm believer in our innocent delicate flower, I'm inclined towards the first option, of course.