Although less common, the phrase can also be used in the negative; as in a "bad face day". However "bad face day" is only used by someone talking about him or herself.
B: "Thanks, I wasn't running late this morning so I had time to put on my makeup."
A:"Ugh, I am having such a bad face day!"
B:"What do you mean?"
A:"Do you not see the huge pimple on my chin and the bags under my eyes?!"