Robin is very secretive. If she lets you know she's having a bad day, it's only because she trusts you so much. She would never want the whole city to hear about such a thing.

It would be...

Very troubling to her.

Imagine something too personal about yourself for me to say out loud. Now imagine I accidentally told the whole city.

Robin's lived as a woman of mystery. She is very strong mentally, so to have any kind of a day that seems less so is incredibly embarrassing, yoi. Her emotional state is always her biggest secret. That is how she hides in plain sight. The truth of such a thing... she would not want that revealed except at her own discretion, eh.