I'd reckon that while she is generally optimistic, she was demonstrated to have no confidence in her abilities to create original designs, which is why she only improved upon other designs rather than creating her own. Considering the number of years of working at her craft without having any true original designs in her name, she likely lost hope of ever being regarded as that great of a fashionista, therefore draining her of her color and hope. The pep she exhibited in the special is clearly greater than the average day due to the fact that her personal hero in the world of fashion walked through her shop's very doors, giving her hope of positive reviews of her work from an expert, as well as tips and encouragement so she can become better at her craft.